IMPORTANCE The association of radiation and chemotherapy with the development of secondary sarcom... more IMPORTANCE The association of radiation and chemotherapy with the development of secondary sarcoma is known, but the contemporary risk has not been well characterized for patients with cancers of the abdomen and pelvis. OBJECTIVE To compare the risk of secondary sarcoma among patients treated with combinations of surgery, radiation, or chemotherapy with patients treated with surgery alone and the general population.
Background: Patients who present to Emergency Departments (ED) after intentional self-harm are at... more Background: Patients who present to Emergency Departments (ED) after intentional self-harm are at an increased risk of dying by suicide. This applies particularly to men, who represent nearly two-thirds of those who die by suicide in Ontario. One way of potentially addressing this gap is to offer a course of blended problem-solving therapy (PST), comprised of a brief course of evidence-based psychotherapy for individuals at-risk for suicide, facilitated by the use of a patient-facing smartphone application and a clinician-facing “dashboard”. This approach has the potential to combine the benefits of face to face therapy and technology to create a novel intervention.Methods: This is a cohort study, nested within a larger pragmatic multicentre pre- and post-design cluster randomized trial (cRCT). Suicidal ideas assessed by the Beck Scale for Suicide Ideation (BSS) is the primary outcome variable. Secondary outcome measures include: depression (PHQ-9); anxiety (GAD-7); PTSD (PC-PTSD); ...
IMPORTANCE Treatment with noninvasive oxygenation strategies such as noninvasive ventilation and ... more IMPORTANCE Treatment with noninvasive oxygenation strategies such as noninvasive ventilation and high-flow nasal oxygen may be more effective than standard oxygen therapy alone in patients with acute hypoxemic respiratory failure. OBJECTIVE To compare the association of noninvasive oxygenation strategies with mortality and endotracheal intubation in adults with acute hypoxemic respiratory failure. DATA SOURCES The following bibliographic databases were searched from inception until April 2020: MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and LILACS. No limits were applied to language, publication year, sex, or race. STUDY SELECTION Randomized clinical trials enrolling adult participants with acute hypoxemic respiratory failure comparing high-flow nasal oxygen, face mask noninvasive ventilation, helmet noninvasive ventilation, or standard oxygen therapy. DATA EXTRACTION AND SYNTHESIS Two reviewers independently extracted individual study data and evaluated studies for risk of bias using the Cochrane Risk of Bias tool. Network meta-analyses using a bayesian framework to derive risk ratios (RRs) and risk differences along with 95% credible intervals (CrIs) were conducted. GRADE methodology was used to rate the certainty in findings. MAIN OUTCOMES AND MEASURES The primary outcome was all-cause mortality up to 90 days. A secondary outcome was endotracheal intubation up to 30 days.
2068 Background: There is limited information on the cost of non-Hodgkin lymphoma (NHL) managemen... more 2068 Background: There is limited information on the cost of non-Hodgkin lymphoma (NHL) management. This study provides population-based estimates of the costs for individuals with NHL from a Canadian perspective using provincial administrative databases. Methods: All individuals residing in Ontario with a diagnosis of first incident NHL from the Ontario Cancer Registry (2005–2009) were matched to non-NHL controls. Matching was based on age (same birth year), geography, income quintile, and resource utilization bands (2 years prior to cancer diagnosis). Each NHL case was matched to a maximum 5 controls. NHL cases from the Ontario Cancer registry were linked with their unique and encrypted health card number to provincial health claims databases (Ontario Ministry of Health and Long-Term Care and Cancer Care Ontario). Resources for this analysis included physician visits, hospitalizations, emergency room visits, medications, home care and same day surgeries. Unit costs (in 2009 Canadi...
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, Jan 10, 2018
Oesophagectomy is a complex operation with the potential for prolonged recovery. The aim of this ... more Oesophagectomy is a complex operation with the potential for prolonged recovery. The aim of this study was to evaluate healthcare resource utilization, specifically emergency department (ED) visits within 1 year of oesophagectomy, and to identify risk factors for ED visits and frequent ED use (FEDU). A retrospective cohort study of consecutive oesophagectomies for cancer in all Ontario hospitals was conducted using linked health data (2000-2012) including the ability to identify ED visits at non-index hospitals. Ontario has a single-payer healthcare system with a population of 13.8-million people. Multivariable regression was used to identify independent factors associated with ED visits and FEDU (≥3 ED visits) within 1 year after oesophagectomy. There were 3344 oesophagectomies with in-hospital mortality of 5.8% (n = 193). Of those discharged, 16.4% (n = 549), 36.0% (n = 1203) and 55.8% (n = 1866) had ED visits within 30 days, 90 days and 1 year, respectively. Higher comorbidity [a...
In the United States, certain minority groups have been shown to have inferior cancer outcomes co... more In the United States, certain minority groups have been shown to have inferior cancer outcomes compared with the white majority population. However, to the authors' knowledge, the majority of research has not separated ethnicity from immigration status. The objective of the current study was to determine the impact of ethnicity, independent of immigration status, on cancer outcomes in Chinese and South Asian populations in Ontario, Canada. The authors conducted a population-based retrospective cohort study using administrative databases in Ontario, Canada. Incident cancer cases were captured in Canadian-born Chinese and South Asian individuals, Chinese and South Asian immigrants, and the general Ontario reference population (non-Chinese/non-South Asian and non-immigrant) between 2000 and 2012. Subjects were followed until death (all-cause and cancer-specific), and Cox proportional hazard models were used to estimate the impact of Chinese and South Asian ethnicity on cancer outco...
252 Background: There is little phase 4 data regarding the toxicity and effectiveness of contempo... more 252 Background: There is little phase 4 data regarding the toxicity and effectiveness of contemporary metastatic castrate-resistant prostate cancer (mCRPC) treatments. We examined hospital admissions and emergency room (ER) visits and survival among patients in the Province of Ontario treated with abiraterone, enzalutamide, docetaxel, or cabazitaxel for mCRPC. Methods: We performed a population-based, retrospective cohort study of 2439 men over the age of 65 treated with abiraterone, enzalutamide, docetaxel, or cabazitaxel for mCRPC from 2003-2015 in Ontario, Canada. Outcomes were toxicity (hospitalizations and ER visits) and overall survival. We used multivariable Cox proportional hazards models with time-varying exposures to calculate hazard ratios (HR). Results: Among 2439 patients, cumulative exposure was greatest for docetaxel (n = 1886 (77.3%); 11,436 person-months), followed by abiraterone (n = 893 (36.6%); 5143 person-months), enzalutamide (n = 52 (2.1%); 351 person-months) ...
To quantify the effect of immortal-time bias in an observational study examining the effect of cu... more To quantify the effect of immortal-time bias in an observational study examining the effect of cumulative testosterone exposure on mortality. We used a population-based matched cohort study of men aged ≥66 years, newly treated with testosterone-replacement therapy (TRT), and matched-controls from 2007 to 2012 in Ontario, Canada to quantify the effects of immortal-time bias. We used generalised estimating equations to determine the association between cumulative TRT exposure and mortality. Results produced by models using time-fixed and time-varying exposures were compared. Further, we undertook a systematic review of PubMed to identify studies addressing immortal-time bias or time-varying exposures in the urological literature and qualitatively summated these. Among 10 311 TRT-exposed men and 28 029 controls, the use of a time-varying exposure resulted in the attenuation of treatment effects compared with an analysis that did not account for immortal-time bias. While both analyses s...
Prior studies have documented inferior health outcomes in vulnerable populations, including racia... more Prior studies have documented inferior health outcomes in vulnerable populations, including racial minorities and those with disadvantaged socioeconomic status. The impact of immigration on cancer-related outcomes is less clear. Administrative databases were linked to create a cohort of incident cancer cases (colorectal, lung, prostate, head and neck, breast, and hematologic malignancies) from 2000 to 2012 in Ontario, Canada. Cancer patients who immigrated to Canada (from 1985 onward) were compared with those who were Canadian born (or immigrated before 1985). Patients were followed from diagnosis until death (cancer-specific or all-cause). Cox proportional hazards models were estimated to determine the impact of immigration on mortality after adjusting for explanatory variables. Additional adjusted models studied the relationship of time since immigration and cancer-specific and overall mortality. From 2000 to 2012, 11,485 cancer cases were diagnosed in recent immigrants (0 to 10 y...
Canadian Journal of Gastroenterology and Hepatology, 2014
BACKGROUND: Postoperative surveillance following curative-intent resection of colorectal cancer (... more BACKGROUND: Postoperative surveillance following curative-intent resection of colorectal cancer (CRC) is variably performed due to existing guideline differences and to the limited data supporting different strategies.OBJECTIVES: To examine population-based rates of surveillance imaging and endoscopy in patients in Ontario following curative-intent resection of CRC with no evidence of recurrence, as well as patient or disease factors that may predispose certain groups to more frequent versus less frequent surveillance; to provide insight to the care patients receive in the presence of conflicting guidelines, in efforts to help improve care of CRC survivors by identifying any potential underuse or overuse of particular surveillance modalities, or inequalities in access to surveillance.METHOD: A retrospective cohort study was conducted using data from the Ontario Cancer Registry and several linked databases. Ontario patients undergoing curative-intent CRC resection from 2003 to 2007 w...
Introduction: Surgical volume can affect several outcomes following radical prostatectomy (RP). W... more Introduction: Surgical volume can affect several outcomes following radical prostatectomy (RP). We examined if surgical volume was associated with novel categories of treatment-related complications following RP.Methods: We examined a population-based cohort of men treated with RP in Ontario, Canada between 2002 and 2009. We used Cox proportional hazard modeling to examine the effect of physician, hospital and patient demographic factors on rates of treatmentrelated hospital admissions, urologic procedures, and open surgeries.Results: Over the study interval, 15 870 men were treated with RP. A total of 196 surgeons performed a median of 15 cases per year (range: 1–131). Patients treated by surgeons in the highest quartile of annual case volume (>39/year) had a lower risk of hospital admission (hazard ratio [HR]=0.54, 95% CI 0.47–0.61) and urologic procedures (HR=0.69, 95% CI 0.64–0.75), but not open surgeries (HR=0.83, 95% CI 0.47‒1.45) than patients treated by surgeons in the lo...
Context: To date, there is no Level 1 evidence comparing the efficacy of radical prostatectomy an... more Context: To date, there is no Level 1 evidence comparing the efficacy of radical prostatectomy and radiotherapy for patients with clinically-localized prostate cancer. Objective: To conduct a meta-analysis assessing the overall and prostate cancer-specific mortality among patients treated with radical prostatectomy or radiotherapy for clinically-localized prostate cancer. Evidence acquisition: We searched Medline, EMBASE, and the Cochrane Library through June 2015 without year or language restriction, supplemented with hand search, using Preferred Reporting Items for Systematic Reviews and Meta-Analysis and Meta-analysis of Observational Studies in Epidemiology guidelines. We used multivariable adjusted hazard ratios (aHRs) to assess each endpoint. Risk of bias was assessed using the Newcastle-Ottawa scale. Evidence synthesis: Nineteen studies of low to moderate risk of bias were selected and up to 118 830 patients were pooled. Inclusion criteria and follow-up length varied between studies. Most studies assessed patients treated with external beam radiotherapy, although some included those treated with brachytherapy separately or with the external beam radiation therapy group. The risk of overall (10 studies, aHR 1.63, 95% confidence interval 1.54-1.73, p < 0.00001; I 2 = 0%) and prostate cancer-specific (15 studies, aHR 2.08, 95% confidence interval 1.76-2.47, p < 0.00001; I 2 = 48%) mortality were higher for patients treated with radiotherapy compared with those treated with surgery. Subgroup analyses by risk group, radiation regimen, time period, and follow-up length did not alter the direction of results. Conclusions: Radiotherapy for prostate cancer is associated with an increased risk of overall and prostate cancer-specific mortality compared with surgery based on observational data with low to moderate risk of bias. These data, combined with the forthcoming randomized data, may aid clinical decision making. Patient summary: We reviewed available studies assessing mortality after prostate cancer treatment with surgery or radiotherapy. While the studies used have a potential for bias due to their observational design, we demonstrated consistently higher mortality for patients treated with radiotherapy rather than surgery.
Background: Regional variation in the use of surgery implies that there is uncertainty regarding ... more Background: Regional variation in the use of surgery implies that there is uncertainty regarding appropriate use. The objectives of this study were to identify which surgical procedures are most commonly performed in the province of Ontario and measure the extent of variation in the use of surgical procedures across Ontario counties. Methods: We used the Canadian Institute for Health Information Discharge Abstract Database, Same Day Surgery Database and National Ambulatory Care Reporting System to retrieve information on all inpatient and day surgery visits in Ontario between Apr. 1, 2002, and Mar. 31, 2011. We identified the 84 most common procedures according to Canadian Classification of Interventions codes. We calculated rates of use for each procedure throughout the 49 Ontario counties and then calculated measures of variation (quartile ratio and systematic component of variation) in use between the counties. Results: Colonoscopy was the most commonly performed procedure during the study period, with an average adjusted rate of 2012 per 100 000 population. The procedure with the highest measure of variation was iridectomy, with a quartile ratio of 6.7, followed by colposcopy (5.2), cervical biopsy (4.2) and femoral arteriography (4.1). These procedures were less commonly performed. Common procedures such as colonoscopy, cataract extraction and vaginal delivery had lower quartile ratios. Analysis using the systematic component of variation as the measure of variation gave similar results. Interpretation: Colonoscopy was the most commonly performed procedure in Ontario, and cataract extraction was the most common surgical procedure. Procedures with the highest measures of variation between counties tended to be those that occurred less commonly in Ontario, and common procedures were associated with less regional variation.
Breast cancer research and treatment, Jan 29, 2015
Validated biomarkers are needed to improve risk assessment and treatment decision-making for wome... more Validated biomarkers are needed to improve risk assessment and treatment decision-making for women with ductal carcinoma in situ (DCIS) of the breast. The Oncotype DX(®) DCIS Score (DS) was shown to predict the risk of local recurrence (LR) in individuals with low-risk DCIS treated by breast-conserving surgery (BCS) alone. Our objective was to confirm these results in a larger population-based cohort of individuals. We used an established population-based cohort of individuals diagnosed with DCIS treated with BCS alone from 1994 to 2003 with validation of treatment and outcomes. Central pathology assessment excluded cases with invasive cancer, DCIS < 2 mm or positive margins. Cox model was used to determine the relationship between independent covariates, the DS (hazard ratio (HR)/50 Cp units (U)) and LR. Tumor blocks were collected for 828 patients. Final evaluable population includes 718 cases, of whom 571 had negative margins. Median follow-up was 9.6 years. 100 cases develope...
A significant share of the cost of cancer care is concentrated in the end-of-life period. Althoug... more A significant share of the cost of cancer care is concentrated in the end-of-life period. Although quality measures of aggressive treatment may guide optimal care during this timeframe, little is known about whether these metrics affect costs of care. This study used population data to identify a cohort of patients who died of cancer in Ontario, Canada (2005-2009). Individuals were categorized as having received or having not received aggressive end-of-life care according to quality measures related to acute institutional care or chemotherapy administration in the end-of-life period. Costs (2009 Canadian dollars) were collected over the last month of life through the linkage of health system administrative databases. Multivariate quantile regression was used to identify predictors of increased costs. Among 107,253 patients, the mean per-patient cost over the final month was $18,131 for patients receiving aggressive care and $12,678 for patients receiving nonaggressive care (P < ....
Goals: Most women with DCIS will be treated by breast-conserving surgery (BCS) often followed by ... more Goals: Most women with DCIS will be treated by breast-conserving surgery (BCS) often followed by radiation. However, BCS alone is an option for individuals with low risk of local recurrence (LR). Validated biomarkers are needed to improve risk assessment and treatment of DCIS. The Oncotype DX ® DCIS Score (DS) was shown to predict the risk of LR in selected individuals treated by BCS alone in the ECOG E5194 clinical trial. Our objective was to confirm these results in a larger population-based cohort of individuals with DCIS treated by BCS alone.
Journal of oncology practice / American Society of Clinical Oncology, 2015
Women with breast cancer often require an extensive diagnostic work-up. We sought to determine th... more Women with breast cancer often require an extensive diagnostic work-up. We sought to determine the overall wait time, from the patient's perspective, from identification of an imaging abnormality to definitive treatment. The objective was to identify which factors contribute to overall wait time in women with breast cancer. A retrospective chart review in a tertiary care center was performed to identify all women who had breast surgery for invasive carcinoma and ductal carcinoma in situ. We recorded the dates of first imaging abnormality, first biopsy, subsequent imaging and biopsy, first consultation with any physician at the cancer center, first surgical consultation, and date of surgery. Clinical data that might influence these dates were then extracted. Wait times were calculated and factors associated with wait times were described. Eligible consecutive women with a cancer diagnosis (n = 264) were identified. The median time between first imaging abnormality and definitive ...
Canadian journal of surgery. Journal canadien de chirurgie, 2008
Preoperative diagnosis of breast cancer is a standard of care. We conducted a population-based st... more Preoperative diagnosis of breast cancer is a standard of care. We conducted a population-based study to determine the factors associated with the use of percutaneous needle biopsy to diagnose breast cancer in Ontario. We identified a total of 3644 women who underwent breast tissue sampling (percutaneous needle biopsy or surgical excision) that yielded a diagnosis of cancer between Apr. 1, 2002, and Dec. 31, 2002, and for whom we were able to obtain complete data. We performed univariate and multivariate analyses to examine the association between a number of variables and the use of percutaneous biopsy or surgery for diagnosis and the performance of biopsy with or without image guidance. The variables were age, local health integration network (LHIN), income quintile, urban or rural residence, access to a primary care provider, prior mammogram, prior regular screening mammography, screen-initiated biopsy, and surgeon and radiologist specialization in breast disease. A total of 2374 ...
also significantly associated with invasive lr (hr: 1.6; 95% ci: 1.0 to 2.4; p = 0.04). Conclusio... more also significantly associated with invasive lr (hr: 1.6; 95% ci: 1.0 to 2.4; p = 0.04). Conclusions Age at diagnosis is a strong predictor of lr in women with dcis after treatment with bcs and radiotherapy.
IMPORTANCE The association of radiation and chemotherapy with the development of secondary sarcom... more IMPORTANCE The association of radiation and chemotherapy with the development of secondary sarcoma is known, but the contemporary risk has not been well characterized for patients with cancers of the abdomen and pelvis. OBJECTIVE To compare the risk of secondary sarcoma among patients treated with combinations of surgery, radiation, or chemotherapy with patients treated with surgery alone and the general population.
Background: Patients who present to Emergency Departments (ED) after intentional self-harm are at... more Background: Patients who present to Emergency Departments (ED) after intentional self-harm are at an increased risk of dying by suicide. This applies particularly to men, who represent nearly two-thirds of those who die by suicide in Ontario. One way of potentially addressing this gap is to offer a course of blended problem-solving therapy (PST), comprised of a brief course of evidence-based psychotherapy for individuals at-risk for suicide, facilitated by the use of a patient-facing smartphone application and a clinician-facing “dashboard”. This approach has the potential to combine the benefits of face to face therapy and technology to create a novel intervention.Methods: This is a cohort study, nested within a larger pragmatic multicentre pre- and post-design cluster randomized trial (cRCT). Suicidal ideas assessed by the Beck Scale for Suicide Ideation (BSS) is the primary outcome variable. Secondary outcome measures include: depression (PHQ-9); anxiety (GAD-7); PTSD (PC-PTSD); ...
IMPORTANCE Treatment with noninvasive oxygenation strategies such as noninvasive ventilation and ... more IMPORTANCE Treatment with noninvasive oxygenation strategies such as noninvasive ventilation and high-flow nasal oxygen may be more effective than standard oxygen therapy alone in patients with acute hypoxemic respiratory failure. OBJECTIVE To compare the association of noninvasive oxygenation strategies with mortality and endotracheal intubation in adults with acute hypoxemic respiratory failure. DATA SOURCES The following bibliographic databases were searched from inception until April 2020: MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and LILACS. No limits were applied to language, publication year, sex, or race. STUDY SELECTION Randomized clinical trials enrolling adult participants with acute hypoxemic respiratory failure comparing high-flow nasal oxygen, face mask noninvasive ventilation, helmet noninvasive ventilation, or standard oxygen therapy. DATA EXTRACTION AND SYNTHESIS Two reviewers independently extracted individual study data and evaluated studies for risk of bias using the Cochrane Risk of Bias tool. Network meta-analyses using a bayesian framework to derive risk ratios (RRs) and risk differences along with 95% credible intervals (CrIs) were conducted. GRADE methodology was used to rate the certainty in findings. MAIN OUTCOMES AND MEASURES The primary outcome was all-cause mortality up to 90 days. A secondary outcome was endotracheal intubation up to 30 days.
2068 Background: There is limited information on the cost of non-Hodgkin lymphoma (NHL) managemen... more 2068 Background: There is limited information on the cost of non-Hodgkin lymphoma (NHL) management. This study provides population-based estimates of the costs for individuals with NHL from a Canadian perspective using provincial administrative databases. Methods: All individuals residing in Ontario with a diagnosis of first incident NHL from the Ontario Cancer Registry (2005–2009) were matched to non-NHL controls. Matching was based on age (same birth year), geography, income quintile, and resource utilization bands (2 years prior to cancer diagnosis). Each NHL case was matched to a maximum 5 controls. NHL cases from the Ontario Cancer registry were linked with their unique and encrypted health card number to provincial health claims databases (Ontario Ministry of Health and Long-Term Care and Cancer Care Ontario). Resources for this analysis included physician visits, hospitalizations, emergency room visits, medications, home care and same day surgeries. Unit costs (in 2009 Canadi...
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, Jan 10, 2018
Oesophagectomy is a complex operation with the potential for prolonged recovery. The aim of this ... more Oesophagectomy is a complex operation with the potential for prolonged recovery. The aim of this study was to evaluate healthcare resource utilization, specifically emergency department (ED) visits within 1 year of oesophagectomy, and to identify risk factors for ED visits and frequent ED use (FEDU). A retrospective cohort study of consecutive oesophagectomies for cancer in all Ontario hospitals was conducted using linked health data (2000-2012) including the ability to identify ED visits at non-index hospitals. Ontario has a single-payer healthcare system with a population of 13.8-million people. Multivariable regression was used to identify independent factors associated with ED visits and FEDU (≥3 ED visits) within 1 year after oesophagectomy. There were 3344 oesophagectomies with in-hospital mortality of 5.8% (n = 193). Of those discharged, 16.4% (n = 549), 36.0% (n = 1203) and 55.8% (n = 1866) had ED visits within 30 days, 90 days and 1 year, respectively. Higher comorbidity [a...
In the United States, certain minority groups have been shown to have inferior cancer outcomes co... more In the United States, certain minority groups have been shown to have inferior cancer outcomes compared with the white majority population. However, to the authors' knowledge, the majority of research has not separated ethnicity from immigration status. The objective of the current study was to determine the impact of ethnicity, independent of immigration status, on cancer outcomes in Chinese and South Asian populations in Ontario, Canada. The authors conducted a population-based retrospective cohort study using administrative databases in Ontario, Canada. Incident cancer cases were captured in Canadian-born Chinese and South Asian individuals, Chinese and South Asian immigrants, and the general Ontario reference population (non-Chinese/non-South Asian and non-immigrant) between 2000 and 2012. Subjects were followed until death (all-cause and cancer-specific), and Cox proportional hazard models were used to estimate the impact of Chinese and South Asian ethnicity on cancer outco...
252 Background: There is little phase 4 data regarding the toxicity and effectiveness of contempo... more 252 Background: There is little phase 4 data regarding the toxicity and effectiveness of contemporary metastatic castrate-resistant prostate cancer (mCRPC) treatments. We examined hospital admissions and emergency room (ER) visits and survival among patients in the Province of Ontario treated with abiraterone, enzalutamide, docetaxel, or cabazitaxel for mCRPC. Methods: We performed a population-based, retrospective cohort study of 2439 men over the age of 65 treated with abiraterone, enzalutamide, docetaxel, or cabazitaxel for mCRPC from 2003-2015 in Ontario, Canada. Outcomes were toxicity (hospitalizations and ER visits) and overall survival. We used multivariable Cox proportional hazards models with time-varying exposures to calculate hazard ratios (HR). Results: Among 2439 patients, cumulative exposure was greatest for docetaxel (n = 1886 (77.3%); 11,436 person-months), followed by abiraterone (n = 893 (36.6%); 5143 person-months), enzalutamide (n = 52 (2.1%); 351 person-months) ...
To quantify the effect of immortal-time bias in an observational study examining the effect of cu... more To quantify the effect of immortal-time bias in an observational study examining the effect of cumulative testosterone exposure on mortality. We used a population-based matched cohort study of men aged ≥66 years, newly treated with testosterone-replacement therapy (TRT), and matched-controls from 2007 to 2012 in Ontario, Canada to quantify the effects of immortal-time bias. We used generalised estimating equations to determine the association between cumulative TRT exposure and mortality. Results produced by models using time-fixed and time-varying exposures were compared. Further, we undertook a systematic review of PubMed to identify studies addressing immortal-time bias or time-varying exposures in the urological literature and qualitatively summated these. Among 10 311 TRT-exposed men and 28 029 controls, the use of a time-varying exposure resulted in the attenuation of treatment effects compared with an analysis that did not account for immortal-time bias. While both analyses s...
Prior studies have documented inferior health outcomes in vulnerable populations, including racia... more Prior studies have documented inferior health outcomes in vulnerable populations, including racial minorities and those with disadvantaged socioeconomic status. The impact of immigration on cancer-related outcomes is less clear. Administrative databases were linked to create a cohort of incident cancer cases (colorectal, lung, prostate, head and neck, breast, and hematologic malignancies) from 2000 to 2012 in Ontario, Canada. Cancer patients who immigrated to Canada (from 1985 onward) were compared with those who were Canadian born (or immigrated before 1985). Patients were followed from diagnosis until death (cancer-specific or all-cause). Cox proportional hazards models were estimated to determine the impact of immigration on mortality after adjusting for explanatory variables. Additional adjusted models studied the relationship of time since immigration and cancer-specific and overall mortality. From 2000 to 2012, 11,485 cancer cases were diagnosed in recent immigrants (0 to 10 y...
Canadian Journal of Gastroenterology and Hepatology, 2014
BACKGROUND: Postoperative surveillance following curative-intent resection of colorectal cancer (... more BACKGROUND: Postoperative surveillance following curative-intent resection of colorectal cancer (CRC) is variably performed due to existing guideline differences and to the limited data supporting different strategies.OBJECTIVES: To examine population-based rates of surveillance imaging and endoscopy in patients in Ontario following curative-intent resection of CRC with no evidence of recurrence, as well as patient or disease factors that may predispose certain groups to more frequent versus less frequent surveillance; to provide insight to the care patients receive in the presence of conflicting guidelines, in efforts to help improve care of CRC survivors by identifying any potential underuse or overuse of particular surveillance modalities, or inequalities in access to surveillance.METHOD: A retrospective cohort study was conducted using data from the Ontario Cancer Registry and several linked databases. Ontario patients undergoing curative-intent CRC resection from 2003 to 2007 w...
Introduction: Surgical volume can affect several outcomes following radical prostatectomy (RP). W... more Introduction: Surgical volume can affect several outcomes following radical prostatectomy (RP). We examined if surgical volume was associated with novel categories of treatment-related complications following RP.Methods: We examined a population-based cohort of men treated with RP in Ontario, Canada between 2002 and 2009. We used Cox proportional hazard modeling to examine the effect of physician, hospital and patient demographic factors on rates of treatmentrelated hospital admissions, urologic procedures, and open surgeries.Results: Over the study interval, 15 870 men were treated with RP. A total of 196 surgeons performed a median of 15 cases per year (range: 1–131). Patients treated by surgeons in the highest quartile of annual case volume (>39/year) had a lower risk of hospital admission (hazard ratio [HR]=0.54, 95% CI 0.47–0.61) and urologic procedures (HR=0.69, 95% CI 0.64–0.75), but not open surgeries (HR=0.83, 95% CI 0.47‒1.45) than patients treated by surgeons in the lo...
Context: To date, there is no Level 1 evidence comparing the efficacy of radical prostatectomy an... more Context: To date, there is no Level 1 evidence comparing the efficacy of radical prostatectomy and radiotherapy for patients with clinically-localized prostate cancer. Objective: To conduct a meta-analysis assessing the overall and prostate cancer-specific mortality among patients treated with radical prostatectomy or radiotherapy for clinically-localized prostate cancer. Evidence acquisition: We searched Medline, EMBASE, and the Cochrane Library through June 2015 without year or language restriction, supplemented with hand search, using Preferred Reporting Items for Systematic Reviews and Meta-Analysis and Meta-analysis of Observational Studies in Epidemiology guidelines. We used multivariable adjusted hazard ratios (aHRs) to assess each endpoint. Risk of bias was assessed using the Newcastle-Ottawa scale. Evidence synthesis: Nineteen studies of low to moderate risk of bias were selected and up to 118 830 patients were pooled. Inclusion criteria and follow-up length varied between studies. Most studies assessed patients treated with external beam radiotherapy, although some included those treated with brachytherapy separately or with the external beam radiation therapy group. The risk of overall (10 studies, aHR 1.63, 95% confidence interval 1.54-1.73, p < 0.00001; I 2 = 0%) and prostate cancer-specific (15 studies, aHR 2.08, 95% confidence interval 1.76-2.47, p < 0.00001; I 2 = 48%) mortality were higher for patients treated with radiotherapy compared with those treated with surgery. Subgroup analyses by risk group, radiation regimen, time period, and follow-up length did not alter the direction of results. Conclusions: Radiotherapy for prostate cancer is associated with an increased risk of overall and prostate cancer-specific mortality compared with surgery based on observational data with low to moderate risk of bias. These data, combined with the forthcoming randomized data, may aid clinical decision making. Patient summary: We reviewed available studies assessing mortality after prostate cancer treatment with surgery or radiotherapy. While the studies used have a potential for bias due to their observational design, we demonstrated consistently higher mortality for patients treated with radiotherapy rather than surgery.
Background: Regional variation in the use of surgery implies that there is uncertainty regarding ... more Background: Regional variation in the use of surgery implies that there is uncertainty regarding appropriate use. The objectives of this study were to identify which surgical procedures are most commonly performed in the province of Ontario and measure the extent of variation in the use of surgical procedures across Ontario counties. Methods: We used the Canadian Institute for Health Information Discharge Abstract Database, Same Day Surgery Database and National Ambulatory Care Reporting System to retrieve information on all inpatient and day surgery visits in Ontario between Apr. 1, 2002, and Mar. 31, 2011. We identified the 84 most common procedures according to Canadian Classification of Interventions codes. We calculated rates of use for each procedure throughout the 49 Ontario counties and then calculated measures of variation (quartile ratio and systematic component of variation) in use between the counties. Results: Colonoscopy was the most commonly performed procedure during the study period, with an average adjusted rate of 2012 per 100 000 population. The procedure with the highest measure of variation was iridectomy, with a quartile ratio of 6.7, followed by colposcopy (5.2), cervical biopsy (4.2) and femoral arteriography (4.1). These procedures were less commonly performed. Common procedures such as colonoscopy, cataract extraction and vaginal delivery had lower quartile ratios. Analysis using the systematic component of variation as the measure of variation gave similar results. Interpretation: Colonoscopy was the most commonly performed procedure in Ontario, and cataract extraction was the most common surgical procedure. Procedures with the highest measures of variation between counties tended to be those that occurred less commonly in Ontario, and common procedures were associated with less regional variation.
Breast cancer research and treatment, Jan 29, 2015
Validated biomarkers are needed to improve risk assessment and treatment decision-making for wome... more Validated biomarkers are needed to improve risk assessment and treatment decision-making for women with ductal carcinoma in situ (DCIS) of the breast. The Oncotype DX(®) DCIS Score (DS) was shown to predict the risk of local recurrence (LR) in individuals with low-risk DCIS treated by breast-conserving surgery (BCS) alone. Our objective was to confirm these results in a larger population-based cohort of individuals. We used an established population-based cohort of individuals diagnosed with DCIS treated with BCS alone from 1994 to 2003 with validation of treatment and outcomes. Central pathology assessment excluded cases with invasive cancer, DCIS < 2 mm or positive margins. Cox model was used to determine the relationship between independent covariates, the DS (hazard ratio (HR)/50 Cp units (U)) and LR. Tumor blocks were collected for 828 patients. Final evaluable population includes 718 cases, of whom 571 had negative margins. Median follow-up was 9.6 years. 100 cases develope...
A significant share of the cost of cancer care is concentrated in the end-of-life period. Althoug... more A significant share of the cost of cancer care is concentrated in the end-of-life period. Although quality measures of aggressive treatment may guide optimal care during this timeframe, little is known about whether these metrics affect costs of care. This study used population data to identify a cohort of patients who died of cancer in Ontario, Canada (2005-2009). Individuals were categorized as having received or having not received aggressive end-of-life care according to quality measures related to acute institutional care or chemotherapy administration in the end-of-life period. Costs (2009 Canadian dollars) were collected over the last month of life through the linkage of health system administrative databases. Multivariate quantile regression was used to identify predictors of increased costs. Among 107,253 patients, the mean per-patient cost over the final month was $18,131 for patients receiving aggressive care and $12,678 for patients receiving nonaggressive care (P < ....
Goals: Most women with DCIS will be treated by breast-conserving surgery (BCS) often followed by ... more Goals: Most women with DCIS will be treated by breast-conserving surgery (BCS) often followed by radiation. However, BCS alone is an option for individuals with low risk of local recurrence (LR). Validated biomarkers are needed to improve risk assessment and treatment of DCIS. The Oncotype DX ® DCIS Score (DS) was shown to predict the risk of LR in selected individuals treated by BCS alone in the ECOG E5194 clinical trial. Our objective was to confirm these results in a larger population-based cohort of individuals with DCIS treated by BCS alone.
Journal of oncology practice / American Society of Clinical Oncology, 2015
Women with breast cancer often require an extensive diagnostic work-up. We sought to determine th... more Women with breast cancer often require an extensive diagnostic work-up. We sought to determine the overall wait time, from the patient's perspective, from identification of an imaging abnormality to definitive treatment. The objective was to identify which factors contribute to overall wait time in women with breast cancer. A retrospective chart review in a tertiary care center was performed to identify all women who had breast surgery for invasive carcinoma and ductal carcinoma in situ. We recorded the dates of first imaging abnormality, first biopsy, subsequent imaging and biopsy, first consultation with any physician at the cancer center, first surgical consultation, and date of surgery. Clinical data that might influence these dates were then extracted. Wait times were calculated and factors associated with wait times were described. Eligible consecutive women with a cancer diagnosis (n = 264) were identified. The median time between first imaging abnormality and definitive ...
Canadian journal of surgery. Journal canadien de chirurgie, 2008
Preoperative diagnosis of breast cancer is a standard of care. We conducted a population-based st... more Preoperative diagnosis of breast cancer is a standard of care. We conducted a population-based study to determine the factors associated with the use of percutaneous needle biopsy to diagnose breast cancer in Ontario. We identified a total of 3644 women who underwent breast tissue sampling (percutaneous needle biopsy or surgical excision) that yielded a diagnosis of cancer between Apr. 1, 2002, and Dec. 31, 2002, and for whom we were able to obtain complete data. We performed univariate and multivariate analyses to examine the association between a number of variables and the use of percutaneous biopsy or surgery for diagnosis and the performance of biopsy with or without image guidance. The variables were age, local health integration network (LHIN), income quintile, urban or rural residence, access to a primary care provider, prior mammogram, prior regular screening mammography, screen-initiated biopsy, and surgeon and radiologist specialization in breast disease. A total of 2374 ...
also significantly associated with invasive lr (hr: 1.6; 95% ci: 1.0 to 2.4; p = 0.04). Conclusio... more also significantly associated with invasive lr (hr: 1.6; 95% ci: 1.0 to 2.4; p = 0.04). Conclusions Age at diagnosis is a strong predictor of lr in women with dcis after treatment with bcs and radiotherapy.
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