A theory-based process evaluation alongside a randomised controlled trial of printed educational messages to increase primary care physicians' prescription of thiazide diuretics for hypertension [ISRCTN72772651].

BACKGROUND: Pragmatic trials of implementation interventions focus on evaluating whether an intervention changes professional behaviour under real-world conditions rather than investigating the mechanism through which change occurs. Theory-based process evaluations conducted alongside pragmatic randomised trials address this by assessing whether the intervention changes theoretical constructs proposed to mediate change. The Ontario Printed Educational Materials (PEM) cluster trial was designed to increase family physicians' guideline-recommended prescription of thiazide diuretics. The trial found no intervention effect. Using the theory of planned behaviour (TPB), we hypothesised that changes in thiazide prescribing would be reflected in changes in intention, consistent with changes in attitude and subjective norm, with no change to their perceived behavioural control (PBC), and tested this alongside the RCT. METHODS: We developed and sent TPB postal questionnaires to a random sub-sample of family physicians in each trial arm 2 months before and 6 months after dissemination of the PEMs. We used analysis of covariance to test for group differences using a 2 × 3 factorial design. We content-analysed an open-ended question about perceived barriers to thiazide prescription. Using control group data, we tested whether baseline measures of TPB constructs predicted self-reported thiazide prescribing at follow-up. RESULTS: Four hundred twenty-six physicians completed pre- and post-intervention questionnaires. Baseline scores on measures of TPB constructs were high: intention mean = 5.9 out of 7 (SD = 1.4), attitude mean = 5.8 (SD = 1.1), subjective norm mean = 5.8 (SD = 1.1) and PBC mean = 6.2 (SD = 1.0). The arms did not significantly differ post-intervention on any of the theory-based constructs, suggesting a possible ceiling effect. Content analysis of perceived barriers suggested post-intentional barriers to prescribing thiazides most often focused on specific patient clinical characteristics and potential side effects. Baseline intention (ß = 0.63, p < 0.01) but not PBC (ß = 0.04, p = 0.78) predicted 42.6 % of the variance in self-reported behaviour at follow-up in the control group. CONCLUSIONS: Congruent with the Ontario Printed Educational Messages trial results and aligned with the TPB, we saw no impact of the intervention on any TPB constructs. The theoretical basis of this evaluation suggests possible explanations for the failure of the PEM intervention to change professional behaviour, which can directly inform the design and content of future theory-based PEM interventions to change professional behaviour. TRIAL REGISTRATION: ISRCTN, Canada ISRCTN72772651.

Printed educational messages fail to increase use of thiazides as first-line medication for hypertension in primary care: a cluster randomized controlled trial [ISRCTN72772651].

BACKGROUND: Evidence on the effectiveness of printed educational messages in contributing to increasing evidence-based clinical practice is contradictory. Nonetheless, these messages flood physician offices, in an attempt to promote treatments that can reduce costs while improving patient outcomes. This study evaluated the ability of printed educational messages to promote the choice of thiazides as the first-line treatment for individuals newly diagnosed with hypertension, a practice supported by good evidence and included in guidelines, and one which could reduce costs to the health care system. METHODS: The study uses a pragmatic, cluster randomized controlled trial (randomized by physician practice group). SETTING: The setting involves all Ontario general/family practice physicians. Messages advising the use of thiazides as the first-line treatment of hypertension were mailed to each physician in conjunction with a widely read professional newsletter. Physicians were randomized to receive differing versions of printed educational messages: an "insert" (two-page evidence-based article) and/or one of two different versions of an "outsert" (short, directive message stapled to the outside of the newsletter). One outsert was developed without an explicit theory and one with messages developed targeting factors from the theory of planned behaviour or neither (newsletter only, with no mention of thiazides). The percentage of patients aged over 65 and newly diagnosed with hypertension who were prescribed a thiazide as the sole initial prescription medication. The effect of the intervention was estimated using a logistic regression model estimated using generalized estimating equation methods to account for the clustering of patients within physician practices. RESULTS: Four thousand five hundred four physicians (with 23,508 patients) were randomized, providing 97 % power to detect a 5 % absolute increase in prescription of thiazides. No intervention effect was detected. Thiazides were prescribed to 27.6 % of the patients who saw control physicians, 27.4 % for the insert, 26.8 % for the outsert and 28.3 % of the patients who saw insert + outsert physicians, p = 0.54. CONCLUSIONS: The study conclusively failed to demonstrate any impact of the printed educational messages on increasing prescribing of thiazide diuretics for first-line management of hypertension. TRIAL REGISTRATION: ISRCTN72772651.

Family physician ethnicity influences quality of diabetes care for Chinese but not South Asian patients.

AIMS: To determine whether sharing the same ethnicity as their family physician influenced the quality of diabetes care for Chinese and South Asian patients in Ontario, Canada. METHODS: We conducted two related studies: a population-based cohort study of Chinese and South Asian patients with incident diabetes using health care administrative data (n=49,484), and a cross-sectional study of Chinese and South Asian patients with established diabetes using data collected directly from their family physicians' clinical records (n=416). In both studies, quality of care measures were compared between patients whose family physicians were or were not from the same ethnic group. RESULTS: In the cohort study, Chinese patients whose family physicians were also Chinese were more likely to have a diabetes-related family physician visit and appropriate HbA1c and cholesterol testing. In the cross-sectional study, they were more likely to have foot examinations, to have microalbuminuria testing, and to achieve recommended treatment targets for HbA1c and for LDL-cholesterol. In contrast, for South Asian patients, most quality measures in either study did not differ by physician ethnicity. CONCLUSIONS: Having a family physician from the same ethnic group was associated with better quality of diabetes care for Chinese but not for South Asian patients.

Looking inside the black box: results of a theory-based process evaluation exploring the results of a randomized controlled trial of printed educational messages to increase primary care physicians' diabetic retinopathy referrals [Trial registration number ISRCTN72772651].

BACKGROUND: Theory-based process evaluations conducted alongside randomized controlled trials provide the opportunity to investigate hypothesized mechanisms of action of interventions, helping to build a cumulative knowledge base and to inform the interpretation of individual trial outcomes. Our objective was to identify the underlying causal mechanisms in a cluster randomized trial of the effectiveness of printed educational materials (PEMs) to increase referral for diabetic retinopathy screening. We hypothesized that the PEMs would increase physicians' intention to refer patients for retinal screening by strengthening their attitude and subjective norm, but not their perceived behavioral control. METHODS: Design: A theory based process evaluation alongside the Ontario Printed Educational Material (OPEM) cluster randomized trial. Postal surveys based on the Theory of Planned Behavior were sent to a random sample of trial participants two months before and six months after they received the intervention. Setting: Family physicians in Ontario, Canada. Participants: 1,512 family physicians (252 per intervention group) from the OPEM trial were invited to participate, and 31.3% (473/1512) responded at time one and time two. The final sample comprised 437 family physicians fully completing questionnaires at both time points. Main Outcome Measures: Primary: behavioral intention related to referring patient for retinopathy screening; secondary: attitude, subjective norm, perceived behavioral control. RESULTS: At baseline, family physicians reported positive intention, attitude, subjective norm, and perceived behavioral control to advise patients about retinopathy screening suggesting limited opportunities for improvement in these constructs. There were no significant differences on intention, attitude, subjective norm, and perceived behavioral control following the intervention. Respondents also reported additional physician- and patient-related factors perceived to influence whether patients received retinopathy screening. CONCLUSIONS: Lack of change in the primary and secondary theory-based outcomes provides an explanation for the lack of observed effect of the main OPEM trial. High baseline levels of intention to advise patients to attend retinopathy screening suggest that post-intentional and other factors may explain gaps in care. Process evaluations based on behavioral theory can provide replicable and generalizable insights to aid interpretation of randomized controlled trials of complex interventions to change health professional behavior. TRIAL REGISTRATION: ISRCTN72772651.

Printed educational messages aimed at family practitioners fail to increase retinal screening among their patients with diabetes: a pragmatic cluster randomized controlled trial [ISRCTN72772651].

BACKGROUND: Evidence of the effectiveness of printed educational messages in narrowing the gap between guideline recommendations and practice is contradictory. Failure to screen for retinopathy exposes primary care patients with diabetes to risk of eye complications. Screening is initiated by referral from family practitioners but adherence to guidelines is suboptimal. We aimed to evaluate the ability of printed educational messages aimed at family doctors to increase retinal screening of primary care patients with diabetes. METHODS: Design: Pragmatic 2×3 factorial cluster trial randomized by physician practice, involving 5,048 general practitioners (with 179,833 patients with diabetes). Setting: Ontario family practitioners. Interventions: Reminders (that retinal screening helps prevent diabetes-related vision loss and is covered by provincial health insurance for patients with diabetes) with prompts to encourage screening were mailed to each physician in conjunction with a widely-read professional newsletter. Alternative printed materials formats were an 'outsert' (short, directive message stapled to the outside of the newsletter), and/or a two-page, evidence-based article ('insert') and a pre-printed sticky note reminder for patients. Main Outcome Measure: A successful outcome was an eye examination (which includes retinal screening) provided to a patient with diabetes, not screened in the previous 12 months, within 90 days after visiting a family practitioner. Analysis accounted for clustering of doctors within practice groups. RESULTS: No intervention effect was detected (eye exam rates were 31.6% for patients of control physicians, 31.3% for the insert, 32.8% for the outsert, 32.3% for those who received both, and 31.2% for those who received both plus the patient reminder with the largest 95% confidence interval around any effect extending from -1.3% to 1.1%). CONCLUSIONS: This large trial conclusively failed to demonstrate any impact of printed educational messages on screening uptake. Despite their low cost, printed educational messages should not be routinely used in attempting to close evidence-practice gaps relating to diabetic retinopathy screening. TRIAL REGISTRATION: ISRCTN72772651.

Inadequate predialysis care and mortality after initiation of renal replacement therapy.

Adequacy of chronic kidney disease (CKD) care is traditionally measured as early or late, but this does not reflect the effect of cumulative or consistent care. Here we relate alternate measures of CKD care to mortality and other outcomes in patients with end-stage renal disease (ESRD) who started renal replacement therapy (RRT) between 1998 and 2008. CKD care was defined traditionally as early or late, and alternatively as cumulative care (total visits) and consistency of care in the critical period immediately prior to start of RRT (consistent critical period care required visits in 3 or more of the 6 months prior to RRT start). The primary outcome was 1-year mortality, with secondary outcomes of inpatient start and access creation. Of 12,143 patients aged 18-97 years at the start of RRT, 75.9% had early CKD care. Only 38.3% of the early group had high cumulative (over 10 visits) and consistent critical period care. The 1-year mortality of 15.8% was more likely with late care, lower cumulative care, and inconsistent critical period care. Both cumulative care and consistent critical period care independently predicted mortality, as well as secondary outcomes. Alternate measures of CKD care are important predictors of outcomes in ESRD and should be considered when reporting adequacy of care. Thus, patients traditionally classified as receiving early CKD care often do not receive adequate care immediately prior to initiating RRT.

Cardiovascular complications and mortality after diabetes diagnosis for South Asian and Chinese patients: a population-based cohort study.

OBJECTIVE: Many non-European ethnic groups have an increased risk for diabetes; however, the published literature demonstrates considerable uncertainty about the rates of diabetes complications among minority populations. The objective of this study was to determine the risks of cardiovascular complications and of mortality after diabetes diagnosis for South Asian and Chinese patients, compared with European patients. RESEARCH DESIGN AND METHODS: A population-based cohort study identified all 491,243 adults with newly diagnosed diabetes in Ontario, Canada, between April 2002 and March 2009. Subjects were followed until March 2011 for the first occurrence of any cardiovascular complication of diabetes (coronary artery disease, stroke, or lower-extremity amputation) and for all-cause mortality. Median follow-up was 4.7 years. RESULTS: The crude incidence of cardiovascular complications after diabetes diagnosis was 17.9 per 1,000 patient-years among European patients, 12.0 among South Asian patients, and 7.7 among Chinese patients. After adjusting for baseline characteristics, the cause-specific hazard ratios (HRs) for cardiovascular complications relative to European patients were 0.95 (95% CI 0.90-1.00; P = 0.056) and 0.50 (0.46-0.53; P < 0.001) for South Asian and Chinese patients, respectively. Mortality was lower for both minority groups (adjusted HR for South Asian patients 0.56 [95% CI 0.52-0.60]; P < 0.001; for Chinese patients 0.58 [0.55-0.62]; P < 0.001). CONCLUSIONS: Chinese patients were at substantially lower risk than European patients for cardiovascular complications after diabetes diagnosis, whereas South Asian patients were at comparable risk. Mortality after diabetes diagnosis was markedly lower for both minority populations.

Absence of disparities in the quality of primary diabetes care for South Asians and Chinese in an urban Canadian setting.

OBJECTIVE: To examine whether quality of diabetes care is equitable for South Asian and Chinese patients in an urban Canadian setting. RESEARCH DESIGN AND METHODS: Process and intermediate measures of quality of care were compared between 246 South Asians, 170 Chinese, and 431 patients from the general population with type 2 diabetes selected from 45 family physicians' practices. RESULTS: A total of 61% of Chinese achieved A1C ≤7.0% versus 45% of South Asians and 49% of the general population (P < 0.05). They were also more likely to achieve LDL cholesterol ≤2.0 mmol/L, while South Asians were more likely to achieve blood pressure ≤130/80. There was only one significant process of care deficiency: fewer foot examinations among South Asians (34 vs. 49% for the general population, P < 0.01). CONCLUSIONS: Quality of diabetes care in a Canadian urban setting was equitable, with ethnic minorities somewhat more likely to achieve recommended targets than the general population.

Variation in the practice of preoperative medical consultation for major elective noncardiac surgery: a population-based study.

BACKGROUND: Patients scheduled for major elective noncardiac surgery frequently undergo preoperative medical consultations. However, the factors that determine whether individuals undergo consultation and the extent of interhospital variation remain unclear. METHODS: The authors used population-based administrative databases to conduct a cohort study of patients, aged 40 yr or older, who underwent major elective noncardiac surgery in Ontario, Canada, between April 2004 and February 2009. Multilevel logistic regression models were used to identify patient- and hospital-level predictors of consultation. RESULTS: Within the cohort of 204,819 patients who underwent surgery at 79 hospitals, 38% (n = 77,965) underwent preoperative medical consultation. Although patient- and surgery-level factors did predict consultation use, they explained only 5.9% of variation in consultation rates. Differences in rates across hospitals were large (range, 10-897 per 1,000 procedures), were not explained by surgical procedure volume or hospital teaching status, and persisted after adjustment for patient- and surgery-level factors. The median odds of undergoing consultation were 3.51 times higher if the same patient had surgery at one randomly selected hospital as opposed to another. CONCLUSIONS: One-third of surgical patients undergo preoperative medical consultation. Although patient- and surgery-level factors are weak predictors of consultation use, the individual hospital is the major determinant of whether patients undergo consultation. Additional research is needed to better understand the basis for this substantial interhospital variation and to determine which patients benefit most from preoperative consultation.

Antipsychotic drugs and the risk of hyperglycemia in older adults without diabetes: a population-based observational study.

OBJECTIVE: To determine whether current antipsychotic use among older persons without diabetes is associated with a higher risk of hospital visits for hyperglycemia, as previous studies in this population have yielded conflicting results. DESIGN, SETTING AND PARTICIPANTS: A nested case-control study within a population-based cohort of persons aged 66 years or older without diabetes, who initiated antipsychotic therapy between April 1, 2002, and March 31, 2006. Cohort members were identified using health databases from Ontario, Canada, and were followed from treatment start until March 31, 2007. MEASUREMENTS: Cases were patients with a hospital visit (emergency department visit or hospital admission) for hyperglycemia. We matched each case with up to 10 controls. We compared the risk of hyperglycemia among current antipsychotic users to that of remote users (discontinued > 180 days). RESULTS: The cohort consisted of 44,121 subjects, mean age of 78.3 years, followed for a mean of 2.2 years. Compared to remote antipsychotic use, current treatment with any antipsychotic was associated with a significantly increased risk of hospital visits for hyperglycemia (adjusted odds ratio [aOR]: 1.52; 95% confidence interval [CI]: 1.07-2.17). The risk was elevated for both atypical (aOR: 1.44; 95% CI: 1.01-2.07) and typical (aOR: 2.86; 95% CI: 1.46-5.59) antipsychotic agents. CONCLUSIONS: Current use of either atypical or typical antipsychotic agents was associated with a significantly increased risk of hospital visits for hyperglycemia among older persons without diabetes. These findings highlight the need for close glucose monitoring during antipsychotic therapy in older populations.

Selection bias explains apparent differential mortality between dialysis modalities.

The relative risk of death for patients treated with peritoneal dialysis compared with those treated with hemodialysis appears to change with duration of dialysis therapy. Patients who start dialysis urgently are at high risk for mortality and are treated almost exclusively with hemodialysis, introducing bias to such mortality comparisons. To better isolate the association between dialysis treatment modality and patient mortality, we examined the relative risk for mortality for peritoneal dialysis compared with hemodialysis among individuals who received ≥4 months of predialysis care and who started dialysis electively as outpatients. From a total of 32,285 individuals who received dialysis in Ontario, Canada during a nearly 8-year period, 6,573 patients met criteria for elective, outpatient initiation. We detected no difference in survival between peritoneal dialysis and hemodialysis after adjusting for relevant baseline characteristics. The relative risk of death did not change with duration of dialysis therapy in our primary analysis, but it did change with time when we defined our patient population using the more inclusive criteria typical of previous studies. These results suggest that peritoneal dialysis and hemodialysis associate with similar survival among incident dialysis patients who initiate dialysis electively, as outpatients, after at least 4 months of predialysis care. Selection bias, rather than an effect of the treatment itself, likely explains the previously described change in the relative risk of death over time between hemodialysis and peritoneal dialysis.

Predicting the risk of 1-year mortality in incident dialysis patients: accounting for case-mix severity in studies using administrative data.

BACKGROUND: Administrative databases are increasingly being used to study the incident dialysis population and have important advantages. However, traditional methods of risk adjustment have limitations in this patient population. OBJECTIVE: Our objective was to develop a prognostic index for 1-year mortality in incident dialysis patients using administrative data that was applicable to ambulatory patients, used objective definitions of candidate predictor variables, and was easily replicated in other environments. RESEARCH DESIGN: Anonymized, administrative health data housed at the Institute for Clinical Evaluative Sciences in Toronto, Canada were used to identify a population-based sample of 16,205 patients who initiated dialysis between July 1, 1998 and March 31, 2005. The cohort was divided into derivation, validation, and testing samples and 4 different strategies were used to derive candidate logistic regression models for 1-year mortality. The final risk prediction model was selected based on discriminatory ability (as measured by the c-statistic) and a risk prediction score was derived using methods adopted from the Framingham Heart Study. Calibration of the predictive model was assessed graphically. RESULTS: The risk of death during the first year of dialysis therapy was 16.4% in the derivation sample. The final model had a c-statistic of 0.765, 0.763, and 0.756 in the derivation, validation, and testing samples, respectively. Plots of actual versus predicted risk of death at 1-year showed good calibration. CONCLUSION: The prognostic index and summary risk score accurately predict 1-year mortality in incident dialysis patients and can be used for the purposes of risk adjustment.

Patient and physician predictors of peritoneal dialysis technique failure: a population based, retrospective cohort study.

BACKGROUND: The use of peritoneal dialysis (PD) has been declining over the past decade in Canada, and high technique failure rates have been implicated. Studies have examined clinical risk factors for PD technique failure, but few studies have addressed sociodemographic factors driving technique failure. There are no studies examining the effect of physician factors on technique failure. METHODS: We conducted a retrospective cohort study using Ontario healthcare databases from 1 April 1995 to 31 March 2005 to examine the effects of patient sociodemographic and physician characteristics on PD technique failure. The primary outcome was time to technique failure. Secondary outcomes included the proportion of patients experiencing technique failure during the first year and the proportion of patients experiencing death during the study period. A competing risks analysis was applied to the Cox proportional hazards model to determine the predictors of technique failure, death, and kidney transplantation. RESULTS: In 5162 incident PD patients, the probability of technique success and patient survival at 5 years was 58.2% and 46.9% respectively. Of patients failing PD, 43.5% failed during the first year of treatment. Statistically significant predictors of technique failure included increasing age [hazard ratio (HR) 1.02], diabetes mellitus (HR 1.32), lower neighborhood education level (HR 2.93), and receiving transient (≤ 3 months) hemodialysis before starting PD (HR 1.24). Predictors of patient death included increasing age (HR 1.05), diabetes mellitus (HR 1.44), coronary artery disease (HR 1.26), congestive heart failure (HR 1.58), and late referral to the nephrologist (HR 1.27). Distance from treating dialysis center and residing in a rural area did not impact the risk of technique failure or death. Male physician gender increased the risk of technique failure (HR 1.31). Increased PD patient volume decreased the risk of technique failure (HR 0.98). None of the physician factors were predictors of patient death. CONCLUSION: These findings support the need for implementing strategies to reduce technique failure, which could include increasing educational resources for patients initiating PD, aggressive risk factor modification in patients with multiple comorbidities, and increasing physician awareness regarding the detrimental outcomes associated with late referral and late PD start.

Outcomes and processes of care related to preoperative medical consultation.

BACKGROUND: Preoperative consultations by internal medicine physicians facilitate documentation of comorbid disease, optimization of medical conditions, risk stratification, and initiation of interventions intended to reduce risk. Nonetheless, the impact of these consultations, which may be performed by general internists or specialists, on outcomes is unclear. METHODS: We used population-based administrative databases to conduct a cohort study of patients 40 years or older who underwent major elective noncardiac surgery in Ontario, Canada, between 1994 and 2004. Propensity scores were used to assemble a matched-pairs cohort that reduced differences between patients who did and did not undergo preoperative consultation by general internists or specialists. The association of consultation with mortality and hospital stay was determined within this matched cohort. As a sensitivity analysis, we evaluated the association of consultation with an outcome for which no difference would be expected: postoperative wound infection. RESULTS: Of 269,866 patients in the cohort, 38.8% (n=104,695) underwent consultation. Within the matched cohort (n=191,852), consultation was associated with increased 30-day mortality (relative risk [RR], 1.16; 95% confidence interval [CI], 1.07-1.25; number needed to harm, 516), 1-year mortality (1.08; 1.04-1.12; number needed to harm, 227), mean hospital stay (difference, 0.67 days; 0.59-0.76), preoperative testing, and preoperative pharmacologic interventions. Notably, consultation was not associated with any difference in postoperative wound infections (RR, 0.98; 95% CI, 0.95-1.02). These findings were stable across subgroups as well as sensitivity analyses that tested for unmeasured confounding. CONCLUSIONS: Medical consultation before major elective noncardiac surgery is associated with increased mortality and hospital stay, as well as increases in preoperative pharmacologic interventions and testing. These findings highlight the need to better understand mechanisms by which consultation influences outcomes and to identify efficacious interventions to decrease perioperative risk.

Using administrative datasets to study outcomes in dialysis patients: a validation study.

BACKGROUND: The use of administrative health data and other secondary data sources to conduct research are increasing, and the quality of these data requires careful scrutiny to ensure that findings of studies based on them are accurate. METHODS: We conducted a multicenter, chart-abstraction study in Ontario, Canada to evaluate the ability of linked administrative databases to identify important baseline demographic and treatment information, changes in dialysis treatment modality over time, and the occurrence of important outcome events in incident dialysis patients. The medical record was considered the reference standard. RESULTS: Within administrative databases, demographic information was very well coded, as was the location where individuals started dialysis, the first treatment modality, the first outpatient modality, and the treatment that was in use 90 days after the start of therapy. The ability to accurately recreate an individual patient's entire dialysis treatment history using physician billing claims was somewhat limited. The treatment changes were often identified in the correct temporal sequence, but the dates that the events occurred did not agree well. Finally, important outcomes including the death and kidney transplantation were captured well, although the recovery of kidney function could not be evaluated because of poor inter-rater reliability. CONCLUSIONS: This validation study provides important information concerning the ability to detect variables related to dialysis care using administrative datasets. Validation work should focus not only on the ability of secondary data to identify baseline comorbidities, but should also attempt to verify that other key variables required to conduct analyses are reliably captured.

Non-invasive cardiac stress testing before elective major non-cardiac surgery: population based cohort study.

OBJECTIVE: To determine the association of non-invasive cardiac stress testing before elective intermediate to high risk non-cardiac surgery with survival and hospital stay. DESIGN: Population based retrospective cohort study. SETTING: Acute care hospitals in Ontario, Canada, between 1 April 1994 and 31 March 2004. PARTICIPANTS: Patients aged 40 years or older who underwent specific elective intermediate to high risk non-cardiac surgical procedures. INTERVENTIONS: Non-invasive cardiac stress testing performed within six months before surgery. MAIN OUTCOME MEASURES: Postoperative one year survival and length of stay in hospital. RESULTS: Of the 271 082 patients in the entire cohort, 23 991 (8.9%) underwent stress testing. After propensity score methods were used to reduce important differences between patients who did or did not undergo preoperative stress testing and assemble a matched cohort (n=46 120), testing was associated with improved one year survival (hazard ratio (HR) 0.92, 95% CI 0.86 to 0.99; P=0.03) and reduced mean hospital stay (difference -0.24 days, 95% CI -0.07 to -0.43; P<0.001). In an analysis of subgroups defined by Revised Cardiac Risk Index (RCRI) class, testing was associated with harm in low risk patients (RCRI 0 points: HR 1.35, 95% CI 1.05 to 1.74), but with benefit in patients who were at intermediate risk (RCRI 1-2 points: 0.92, 95% CI 0.85 to 0.99) or high risk (RCRI 3-6 points: 0.80, 95% CI 0.67 to 0.97). CONCLUSIONS: Preoperative non-invasive cardiac stress testing is associated with improved one year survival and length of hospital stay in patients undergoing elective intermediate to high risk non-cardiac surgery. These benefits principally apply to patients with risk factors for perioperative cardiac complications.

Income-related differences in mortality among people with diabetes mellitus.

BACKGROUND: Mortality has declined substantially among people with diabetes mellitus over the last decade. Whether all income groups have benefited equally, however, is unclear. We examined the impact of income on mortality trends among people with diabetes. METHODS: In this population-based, retrospective cohort study, we compared changes in mortality from Apr. 1, 1994, to Mar. 31, 2005, by neighbourhood income strata among people with diabetes aged 30 years or more in the province of Ontario, Canada. RESULTS: Overall, the annual age- and sex-adjusted mortality declined, from 4.05% in 1994/95 (95% confidence interval [CI] 3.98%-4.11%) to 2.69% in 2005/06 (95% CI 2.66%-2.73%). The decrease was significantly greater in the highest income group (by 36%) than in the lowest income group (by 31%; p < 0.001). This trend was most pronounced in the younger group (age 30-64 years): the mortality rate ratio widened by more than 40% between the lowest and highest income groups, from 1.12 to 1.59 among women and from 1.14 to 1.60 among men. Income had a much smaller effect on mortality trends in the older group, whose drug costs are subsidized: the income-related difference rose by only 0.9% over the study period. INTERPRETATION: Mortality declined overall among people with diabetes from 1994 to 2005; however, the decrease was substantially greater in the highest income group than in the lowest, particularly among those aged 30-64 years. These findings illustrate the increasing impact of income on the health of people with diabetes even in a publicly funded health care setting. Further studies are needed to explore factors responsible for these income-related differences in mortality.

Development of an algorithm to identify preoperative medical consultations using administrative data.

BACKGROUND: Preoperative consultation by internal medicine specialists may help improve the care of patients undergoing major surgery. Population-based administrative data are an efficient approach for studying these consultations at a population-level. However, administrative data in many jurisdictions lack specific codes to identify preoperative medical consultations, as opposed to consultations for nonoperative indications. OBJECTIVE: To develop an accurate claims-based algorithm for identifying preoperative medical consultations before major elective noncardiac surgery. RESEARCH DESIGN: We conducted a multicenter cross-sectional study in Ontario, Canada. Preoperative medical consultations identified by medical record abstraction were compared with those identified by linked administrative data (physician service claims, hospital discharge abstracts). SUBJECTS: We randomly selected 606 individuals, aged older than 40 years, who underwent elective intermediate-to-high-risk noncardiac surgery at 8 randomly selected hospitals between April 1, 2002 and March 31, 2004. RESULTS: Medical record abstraction identified preoperative medical consultations in 317 patients (52%). The optimal claims-based algorithm for identifying these consultations was a physician service claim for a consultation by a cardiologist, general internist, endocrinologist, geriatrician, or nephrologist within 4 months before the index surgical procedure. This algorithm had a sensitivity of 90% (95% confidence interval [CI]: 86-93), specificity of 92% (95% CI: 88-95), positive predictive value of 93% (95% CI: 89-95), and negative predictive value of 90% (95% CI: 86-93). CONCLUSIONS: A simple claims-based algorithm can accurately identify preoperative medical consultations before major elective noncardiac surgery. This algorithm may help enhance population-based evaluations of preoperative care, provided that the requisite linked administrative healthcare data are present.

Adverse cardiovascular events during treatment with pioglitazone and rosiglitazone: population based cohort study.

OBJECTIVE: To compare the risk of acute myocardial infarction, heart failure, and death in patients with type 2 diabetes treated with rosiglitazone and pioglitazone. DESIGN: Retrospective cohort study. SETTING: Ontario, Canada. PARTICIPANTS: Outpatients aged 66 years and older who were started on rosiglitazone or pioglitazone between 1 April 2002 and 31 March 2008. MAIN OUTCOME MEASURE: Composite of death or hospital admission for either acute myocardial infarction or heart failure. In a secondary analysis, each outcome was also examined individually. RESULTS: 39 736 patients who started on either pioglitazone or rosiglitazone were identified. During the six year study period, the composite outcome was reached in 895 (5.3%) of patients taking pioglitazone and 1563 (6.9%) of patients taking rosiglitazone. After extensive adjustment for demographic and clinical factors and drug doses, pioglitazone treated patients had a lower risk of developing the primary outcome than did patients treated with rosiglitazone (adjusted hazard ratio 0.83, 95% confidence interval 0.76 to 0.90). Secondary analyses revealed a lower risk of death (adjusted hazard ratio 0.86, 0.75 to 0.98) and heart failure (0.77, 0.69 to 0.87) with pioglitazone but no significant difference in the risk of acute myocardial infarction (0.95, 0.81 to 1.11). One additional composite outcome would be predicted to occur annually for every 93 patients treated with rosiglitazone rather than pioglitazone. CONCLUSIONS: Among older patients with diabetes, pioglitazone is associated with a significantly lower risk of heart failure and death than is rosiglitazone. Given that rosiglitazone lacks a distinct clinical advantage over pioglitazone, continued use of rosiglitazone may not be justified.