Onyebuchi A. Arah

Severe hypoglycaemia and cardiovascular disease: systematic review and meta-analysis with bias analysis

Objectives To provide a systematic and quantitative summary of the association between severe hypoglycaemia and risk of cardiovascular disease in people with type 2 diabetes and to examine the sensitivity of the association to possible uncontrolled confounding by unmeasured comorbid severe illness using a bias analysis. Design Meta-analysis of observational studies. Data sources Medline, Embase, the Cochrane Library, and Web of Science databases were searched to February 2013, without any language restrictions. Eligibility criteria Two independent reviewers selected cohort studies that evaluated the association of severe hypoglycaemia with cardiovascular events in people with type 2 diabetes; we excluded studies from acute hospital settings. We extracted descriptive and quantitative data. Results Of 3443 citations screened, six eligible studies with 903 510 participants were identified. In the conventional random effects meta-analysis, severe hypoglycaemia was strongly associated with a higher risk of cardiovascular disease (relative risk 2.05, 95% confidence interval 1.74 to 2.42; P<0.001). The excess fraction of cardiovascular disease incidence that was attributable to severe hypoglycaemia (the population attributable fraction) was 1.56% (95% confidence interval 1.32% to 1.81%; P<0.001). Although moderate heterogeneity across the studies was suggested (I2=73.1%; P=0.002 for heterogeneity), most subgroups showed similar results in stratified analyses. The bias analysis indicated that comorbid severe illness alone may not explain the association between hypoglycaemia and cardiovascular disease; to explain this association, comorbid severe illness would have had to be extremely strongly associated with both severe hypoglycaemia and cardiovascular disease. Conclusion Our findings suggest that severe hypoglycaemia is associated with a higher risk of cardiovascular disease; they also support the notion that avoiding severe hypoglycaemia may be important to prevent cardiovascular disease in people with type 2 diabetes.

Bias formulas for sensitivity analysis of unmeasured confounding for general outcomes, treatments, and confounders.

Uncontrolled confounding in observational studies gives rise to biased effect estimates. Sensitivity analysis techniques can be useful in assessing the magnitude of these biases. In this paper, we use the potential outcomes framework to derive a general class of sensitivity-analysis formulas for outcomes, treatments, and measured and unmeasured confounding variables that may be categorical or continuous. We give results for additive, risk-ratio and odds-ratio scales. We show that these results encompass a number of more specific sensitivity-analysis methods in the statistics and epidemiology literature. The applicability, usefulness, and limits of the bias-adjustment formulas are discussed. We illustrate the sensitivity-analysis techniques that follow from our results by applying them to 3 different studies. The bias formulas are particularly simple and easy to use in settings in which the unmeasured confounding variable is binary with constant effect on the outcome across treatment levels.

Doctor performance assessment in daily practise : Does it help doctors or not? A systematic review

Context  Continuous assessment of individual performance of doctors is crucial for life‐long learning and quality of care. Policy‐makers and health educators should have good insights into the strengths and weaknesses of the methods available. The aim of this study was to systematically evaluate the feasibility of methods, the psychometric properties of instruments that are especially important for summative assessments, and the effectiveness of methods serving formative assessments used in routine practise to assess the performance of individual doctors.

Doctors' perceptions of why 360-degree feedback does (not) work: a qualitative study.

Objectives  Delivery of 360‐degree feedback is widely used in revalidation programmes. However, little has been done to systematically identify the variables that influence whether or not performance improvement is actually achieved after such assessments. This study aims to explore which factors represent incentives, or disincentives, for consultants to implement suggestions for improvement from 360‐degree feedback.

Bias formulas for external adjustment and sensitivity analysis of unmeasured confounders.

PURPOSE Uncontrolled confounders are an important source of bias in epidemiologic studies. The authors review and derive a set of parallel simple formulas for bias factors in the risk difference, risk ratio, and odds ratio from studies with an unmeasured polytomous confounder and a dichotomous exposure and outcome. METHODS The authors show how the bias formulas are related to and are sometimes simpler than earlier formulas. The article contains three examples, including a Monte Carlo sensitivity analysis of a preadjusted or conditional estimate. RESULTS All the bias expressions can be given parallel formulations as the difference or ratio of (i) the sum across confounder strata of each exposure-stratified confounder-outcome effect measure multiplied by the confounder prevalences among the exposed and (ii) the sum across confounder strata of the same effect measure multiplied by the confounder prevalences among the unexposed. The basic formulas can be applied to scenarios with a polytomous confounder, exposure, or outcome. CONCLUSIONS In addition to aiding design and analysis strategies for confounder control, the bias formulas provide a link between classical standardization decompositions of demography and classical bias formulas of epidemiology. They are also useful in constructing general programs for sensitivity analysis and more elaborate probabilistic risk analyses.

Patterns and predictors of early mortality in incident hemodialysis patients: new insights.

Background: Incident hemodialysis patients have the highest mortality in the first several months after starting dialysis treatments. We hypothesized that the patterns and risk factors associated with this early mortality differ from those in later dialysis therapy periods. Methods: We examined mortality patterns and predictors during the first several months of hemodialysis treatment in 18,707 incident patients since the first week of hemodialysis therapy and estimated the population attributable fractions for selected time periods in the first 24 months. Results: The 18,707 incident hemodialysis patients were 45% women and 54% diabetics. The standardized mortality ratios (95% confidence interval) in the 1st to 3rd month of hemodialysis therapy were 1.81 (1.74–1.88), 1.79 (1.72–1.86), and 1.34 (1.27–1.40), respectively. The standardized mortality ratio reached prevalent mortality only by the 7th month. No survival advantage for African Americans existed in the first 6 months. Patients with low albumin <3.5 g/dl had the highest proportion of infection-related deaths while patients with higher albumin levels had higher cardiovascular deaths including 76% of deaths during the first 3 months. Use of catheter as vascular access and hypoalbuminemia <3.5 g/dl explained 34% (17–54%) and 33% (19–45%) of all deaths in the first 90 days, respectively. Conclusions: Incident hemodialysis patients have the highest mortality during the first 6 months including 80% higher death risk in the first 2 months. The presence of a central venous catheter and hypoalbuminemia <3.5 g/dl each explain one third of all deaths in the first 90 days.

Parkinson disease and smoking revisited Ease of quitting is an early sign of the disease

Objective: To assess whether being able to quit smoking is an early marker of Parkinson disease (PD) onset rather than tobacco being “neuroprotective,” we analyzed information about ease of quitting and nicotine substitute use. Methods: For this case-control study, we identified 1,808 patients with PD diagnosed between 1996 and 2009 from Danish registries, matched 1,876 population controls on sex and year of birth, and collected lifestyle information. We estimated odds ratios and 95% confidence intervals with logistic regression adjusting for matching factors and confounders. Results: Fewer patients with PD than controls ever established a smoking habit. Among former smokers, those with greater difficulty quitting or using nicotine substitutes were less likely to develop PD, with the risk being lowest among those reporting “extremely difficult to quit” compared with “easy to quit.” Nicotine substitute usage was strongly associated with quitting difficulty and duration of smoking, i.e., most strongly among current smokers, followed by former smokers who had used nicotine substitutes, and less strongly among former smokers who never used substitutes. Conclusions: Our data support the notion that patients with PD are able to quit smoking more easily than controls. These findings are compatible with a decreased responsiveness to nicotine during the prodromal phase of PD. We propose that ease of smoking cessation is an aspect of premanifest PD similar to olfactory dysfunction, REM sleep disorders, or constipation and suggests that the apparent “neuroprotective” effect of smoking observed in epidemiologic studies is due to reverse causation.

Racial and Ethnic Differences in the Association of Body Mass Index and Survival in Maintenance Hemodialysis Patients

BACKGROUND In maintenance hemodialysis (HD) patients, overweight and obesity are associated with survival advantages. Given the greater survival of maintenance HD patients who are minorities, we hypothesized that increased body mass index (BMI) is associated more strongly with lower mortality in blacks and Hispanics relative to non-Hispanic whites. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS We examined a 6-year (2001-2007) cohort of 109,605 maintenance HD patients including 39,090 blacks, 17,417 Hispanics, and 53,098 non-Hispanic white maintenance HD outpatients from DaVita dialysis clinics. Cox proportional hazards models examined the association between BMI and survival. PREDICTORS Race and BMI. OUTCOMES All-cause mortality. RESULTS Patients had a mean age of 62 ± 15 (standard deviation) years and included 45% women and 45% patients with diabetes. Across 10 a priori-selected BMI categories (<18-≥40 kg/m(2)), higher BMI was associated with greater survival in all 3 racial/ethnic groups. However, Hispanic and black patients experienced higher survival gains compared with non-Hispanic whites across higher BMI categories. Hispanics and blacks in the ≥40-kg/m(2) category had the largest adjusted decrease in death HR with increasing BMI (0.57 [95% CI, 0.49-0.68] and 0.63 [95% CI, 0.58-0.70], respectively) compared with non-Hispanic whites in the 23- to 25-kg/m(2) group (reference category). In linear models, although the inverse BMI-mortality association was observed for all subgroups, overall black maintenance HD patients showed the largest consistent decrease in death HR with increasing BMI. LIMITATIONS Race and ethnicity categories were based on self-identified data. CONCLUSIONS Whereas the survival advantage of high BMI is consistent across all racial/ethnic groups, black maintenance HD patients had the strongest and most consistent association of higher BMI with improved survival.

Three methods of multi-source feedback compared: a plea for narrative comments and coworkers' perspectives

Background: Doctor performance assessments based on multi-source feedback (MSF) are increasingly central in professional self-regulation. Research has shown that simple MSF is often unproductive. It has been suggested that MSF should be delivered by a facilitator and combined with a portfolio. Aims: To compare three methods of MSF for consultants in the Netherlands and evaluate the feasibility, topics addressed and perceived impact upon clinical practice. Method: In 2007, 38 facilitators and 109 consultants participated in the study. The performance assessment system was composed of (i) one of the three MSF methods, namely, Violatos Physician Achievement Review (PAR), the method developed by Ramsey et al. for the American Board of Internal Medicine (ABIM), or the Dutch Appraisal and Assessment Instrument (AAI), (ii) portfolio, (iii) assessment interview with a facilitator and (iv) personal development plan. The evaluation consisted of a postal survey for facilitators and consultants. Generalized estimating equations were used to assess the association between MSF method used and perceived impact. Results: It takes on average 8 hours to conduct one assessment. The CanMEDS roles ‘collaborator’, ‘communicator’ and ‘manager’ were discussed in, respectively, 79, 74 and 71% of the assessment interviews. The ‘health advocate role’ was the subject of conversation in 35% of the interviews. Consultants are more satisfied with feedback that contains narrative comments. The perceived impact of MSF that includes coworkers’ perspectives significantly exceeds the perceived impact of methods not including this perspective. Conclusions: Performance assessments based on MSF combined with a portfolio and a facilitator-led interview seem to be feasible in hospital settings. The perceived impact of MSF increases when it contains coworkers’ perspectives.

A Systematic Review of the Impact of Physicians’ Occupational Well-Being on the Quality of Patient Care

BackgroundIt is widely held that the occupational well-being of physicians may affect the quality of their patient care. Yet, there is still no comprehensive synthesis of the evidence on this connection.PurposeThis systematic review studied the effect of physicians’ occupational well-being on the quality of patient care.MethodsWe systematically searched PubMed, Embase, and PsychINFO from inception until August 2014. Two authors independently reviewed the studies. Empirical studies that explored the association between physicians’ occupational well-being and patient care quality were considered eligible. Data were systematically extracted on study design, participants, measurements, and findings. The Medical Education Research Study Quality Instrument (MERSQI) was used to assess study quality.ResultsUltimately, 18 studies were included. Most studies employed an observational design and were of average quality. Most studies reported positive associations of occupational well-being with patient satisfaction, patient adherence to treatment, and interpersonal aspects of patient care. Studies reported conflicting findings for occupational well-being in relation to technical aspects of patient care. One study found no association between occupational well-being and patient health outcomes.ConclusionsThe association between physicians’ occupational well-being and health care’s ultimate goal—improved patient health—remains understudied. Nonetheless, research up till date indicated that physicians’ occupational well-being can contribute to better patient satisfaction and interpersonal aspects of care. These insights may help in shaping the policies on physicians’ well-being and quality of care.