Susan Samuel

Exploring physician specialist response rates to web-based surveys

BackgroundSurvey research in healthcare is an important tool to collect information about healthcare delivery, service use and overall issues relating to quality of care. Unfortunately, physicians are often a group with low survey response rates and little research has looked at response rates among physician specialists. For these reasons, the purpose of this project was to explore survey response rates among physician specialists in a large metropolitan Canadian city.MethodsAs part of a larger project to look at physician payment plans, an online survey about medical billing practices was distributed to 904 physicians from various medical specialties. The primary method for physicians to complete the survey was via the Internet using a well-known and established survey company (www.surveymonkey.com). Multiple methods were used to encourage survey response such as individual personalized email invitations, multiple reminders, and a draw for three gift certificate prizes were used to increase response rate. Descriptive statistics were used to assess response rates and reasons for non-response.ResultsOverall survey response rate was 35.0%. Response rates varied by specialty: Neurology/neurosurgery (46.6%); internal medicine (42.9%); general surgery (29.6%); pediatrics (29.2%); and psychiatry (27.1%). Non-respondents listed lack of time/survey burden as the main reason for not responding to our survey.ConclusionsOur survey results provide a look into the challenges of collecting healthcare research where response rates to surveys are often low. The findings presented here should help researchers in planning future survey based studies. Findings from this study and others suggest smaller monetary incentives for each individual may be a more appropriate way to increase response rates.

Contrast-Induced Acute Kidney Injury and Risk of Adverse Clinical Outcomes After Coronary Angiography A Systematic Review and Meta-Analysis

Background—Contrast-induced acute kidney injury (CI-AKI) has been associated with mortality, although it has been suggested this association may be attributable to confounding. We performed a systematic review and meta-analysis to characterize the associations between CI-AKI and subsequent clinical outcomes. Methods and Results—We identified studies using MEDLINE (1950 to June 2011) and Embase (1980 to June 2011), manual bibliographic searches, and contact with experts. We included observational studies that characterized outcomes among patients with and without AKI (based on changes in serum creatinine) after coronary angiography. Eligible studies reported at least 1 of mortality, cardiovascular events, end-stage renal disease, or length of hospital stay. Thirty-nine observational studies met inclusion criteria. Of 34 studies reporting mortality (including 139 603 participants), 33 reported an increased risk of death in those with CI-AKI, although the effect size varied between studies (I2=93.5%). Between-study heterogeneity was partially explained by whether adjustment for confounding features was performed (11 studies without adjustment; pooled crude risk ratio, 8.19; 95% confidence interval, 4.30–15.60; I2=77.3% versus 23 studies with adjustment; pooled adjusted risk ratio, 2.39; 95% confidence interval, 1.98–2.90; I2=88.3%). CI-AKI was consistently associated with an increased risk of cardiovascular events in 14 studies, end-stage renal disease in 3 studies, and prolonged hospitalization in 11 studies. Conclusions—CI-AKI is associated with an increased risk of mortality, cardiovascular events, renal failure, and prolonged hospitalization. However, the association between CI-AKI and mortality is strongly confounded by baseline clinical characteristics that simultaneously predispose to both kidney injury and mortality, and the risk attributable to CI-AKI is much lower than that reported from unadjusted studies.

Kidney stones and kidney function loss: a cohort study

Objective To investigate whether the presence of kidney stones increase the risk of end stage renal disease (ESRD) or other adverse renal outcomes. Design A registry cohort study using validated algorithms based on claims and facility utilisation data. Median follow-up of 11 years. Setting Alberta, Canada, between 1997 and 2009. Participants 3 089 194 adult patients without ESRD at baseline or a history of pyelonephritis. Of these, 1 954 836 had outpatient serum creatinine measurements and were included in analyses of chronic kidney disease and doubling of serum creatinine level. Exposure One or more kidney stones during follow-up. Main outcome measures Incident ESRD, development of stage 3b–5 chronic kidney disease (estimated glomerular filtration rate <45 mL/min/1.73 m2), and sustained doubling of serum creatinine concentration from baseline. Results 23 706 (0.8%) patients had at least one kidney stone, 5333 (0.2%) developed ESRD, 68 525 (4%) developed stage 3b–5 chronic kidney disease, and 6581 (0.3%) experienced sustained doubling of serum creatinine. Overall, one or more stone episodes during follow-up was associated with increased risk of ESRD (adjusted hazard ratio 2.16 (95% CI 1.79 to 2.62)), new stage 3b–5 chronic kidney disease (hazard ratio 1.74 (1.61 to 1.88)), and doubling of serum creatinine (hazard ratio 1.94 (1.56 to 2.43)), all compared with those without kidney stones during follow-up. The excess risk of adverse outcomes associated with at least one episode of stones seemed greater in women than in men, and in people aged <50 years than in those aged ≥50. However, the risks of all three adverse outcomes in those with at least one episode of stones were significantly higher than in those without stones in both sexes and age strata. The absolute increase in the rate of adverse renal outcomes associated with stones was small: the unadjusted rate of ESRD was 2.48 per million person days in people with one or more episodes of stones versus 0.52 per million person days in people without stones. Conclusion Even a single kidney stone episode during follow-up was associated with a significant increase in the likelihood of adverse renal outcomes including ESRD. However, the increases were small in absolute terms.

Association between age and graft failure rates in young kidney transplant recipients.

Background. Age at transplant and graft failure risk are associated in young kidney transplant recipients. The risk of graft failure may also vary by current age, irrespective of age at transplant. We sought to estimate age-specific graft failure rates in young kidney transplant recipients and to estimate the relative hazards of graft failure at different ages, compared with at the age of 25 to 29 years. Methods. We evaluated 90,689 patients recorded in the United States Renal Data System database who received a first transplant when younger than 40 years (1988–2009); 18,310 were younger than 21 years at transplant. Time-dependent Cox models with time-varying covariates were used to estimate the association between age (time-dependent) and death-censored graft failure risk, adjusted for time since transplant and other potential confounders. Results. There were 31,857 graft failures over a median follow-up of 5.9 years (interquartile range, 2.5–10.5 years; maximum, 21.8 years). Crude age-specific graft failure rates were highest in 19 year olds (6.6 per 100 person-years). Compared with individuals with the same time since transplant observed at 25 to 29 years of age, death-censored graft failure rates were highest in 17 to 24 year olds (hazard ratio, 1.20; [95% confidence interval 1.13, 1.27] for 17–20 year olds and 1.20 [1.13, 1.26] for 21–24 year olds; both P<0.0001) and lowest in 5 to 12 year olds (hazard ratio, 0.60; [0.53, 0.68] for 5–9 year olds and 0.56 [0.49, 0.64] for 10–12 year olds; both P<0.0001). Conclusion. Among first kidney transplant recipients younger than 40 years, older adolescents and young adults (17–24 years) have the highest risk of graft failure, irrespective of age at transplant.

Kidney Stones and Cardiovascular Events: A Cohort Study

BACKGROUND AND OBJECTIVES Kidney stones are common in general clinical practice, and their prevalence is increasing. Kidney stone formers often have risk factors associated with atherosclerosis, but it is uncertain whether having a kidney stone is associated with higher risk of cardiovascular events. This study sought to assess the association between one or more kidney stones and the subsequent risk of cardiovascular events. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Cohort study of 3,195,452 people aged≥18 years registered in the universal health care system in Alberta, Canada, between 1997 and 2009 (median follow-up of 11 years). People undergoing dialysis or with a kidney transplant at baseline were excluded. The primary outcome was the first acute myocardial infarction (AMI) during follow-up. We also considered other cardiovascular events, including death due to coronary heart disease, percutaneous transluminal coronary angioplasty (PTCA), coronary artery bypass grafting (CABG), and stroke. RESULTS In total, 25,532 (0.8%) participants had at least one kidney stone, and 91,465 (3%) individuals had at least one cardiovascular event during follow-up. Compared with people without kidney stones and after adjustment for cardiovascular risk factors and other potential confounders, people who had at least one kidney stone had a higher risk of subsequent AMI (adjusted hazard ratio [HR], 1.40; 95% confidence interval [95% CI], 1.30 to 1.51), PTCA/CABG (HR, 1.63; 95% CI, 1.51 to 1.76), and stroke (HR, 1.26; 95% CI, 1.12 to 1.42). The magnitude of the excess risk associated with a kidney stone appeared more pronounced for younger people than for older people (P<0.001) and for women than men (P=0.01). CONCLUSIONS The occurrence of a kidney stone is associated with a higher risk of cardiovascular events, including AMI, PTCA/CABG, and stroke.

Survival in pediatric dialysis and transplant patients.

BACKGROUND AND OBJECTIVES Long-term follow-up data are few in children with ESRD. We sought to describe long-term survival, assess risk factors for death, and compare survival between two time periods in pediatric ESRD patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We used a population-based retrospective cohort utilizing data from a national organ failure registry and from Canadas universal healthcare system. We included 843 children (ages, 0 to 18) initiating renal replacement therapy from 1992 to 2007 and followed them until death or date of last contact (median follow-up, 6.8 years; interquartile range, 3.0 to 10.6). We assessed risk factors for death and examined cause-specific mortality. RESULTS During 5991 patient-years of follow-up, 107 (12.7%) patients died. Unadjusted cumulative survival for the cohort was: 91.7% (95% CI, 89.8 to 93.7%) at 5 years and 85.8% (95% CI, 82.8 to 88.8%) at 10 years. Among patients commencing dialysis, overall adjusted survival was poorest among those who started dialysis at age <1 year. No secular trends in survival were noted for either dialysis or transplant patients. The proportion of incident patients receiving pre-emptive transplantation increased over time. Pre-emptively transplanted patients did not demonstrate superior adjusted survival compared with those who spent >2 years on dialysis before transplant (hazard ratio, 1.53; 95% CI, 0.63 to 3.67). CONCLUSIONS No significant improvements in survival were observed among ESRD patients over the study period. Time with transplant function had the strongest association with survival. Pre-emptive transplantation was not associated with improved survival in adjusted models.

Graft failure and adaptation period to adult healthcare centers in pediatric renal transplant patients.

Background. Transfer from pediatric to adult care may require a period of adaptation to the new healthcare environment. We sought to determine whether this adaptation period was associated with an increased risk of graft failure. Methods. Children (age, 0–18 years) recorded in the Canadian Organ Replacement Register who received a first kidney transplant in a pediatric health center between 1992 and 2007, and who had more than or equal to 3 months of graft function, were followed up until death, loss to follow-up, or December 31, 2007. Cox proportional hazards models were used to estimate the excess risk associated with a period of adaptation to adult-oriented care, defined as the interval 0.5 years before to 2.5 years after the first recorded adult care visit. Models were adjusted for age, gender, donor source, and ethnicity. Results. Of the 413 patients evaluated, 149 were transferred to adult care during study period. In total, 78 (18.9%) patients experienced graft failure—23 during the adaptation period. Compared with the period before adaptation, the adjusted hazard ratio for graft loss within the adaptation period was 2.24 (95% confidence interval [CI]: 1.19–4.20). The adjusted graft failure rate was 2.26 (1.04–4.93) times higher after 18 years of age than between 0 and 13 years. Aboriginal ethnicity and deceased donor source were also associated with a significantly higher risk of graft failure. Conclusions. The period of adaptation to adult-oriented care is associated with a high risk of graft failure in pediatric renal transplant patients.

Validating a case definition for chronic kidney disease using administrative data

BACKGROUND Administrative data are commonly used for surveillance of chronic medical conditions. The purpose of this study was to determine the validity of an algorithm derived from administrative data for identifying chronic kidney disease (CKD) compared to the reference standard of estimated glomerular filtration rate (eGFR). METHODS We identified adults from the province of Alberta with at least two outpatient serum creatinine measurements within a 1-year time period. Validity indices were estimated for CKD using up to 3 years of administrative data (physician billing claims and hospital discharge abstracts) for various case-definition combinations. For each algorithm, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated against two reference standard definitions of CKD (two eGFR measurements <60 mL/min/1.73m(2) or mean eGFR < 30 mL/min/1.73m(2)). RESULTS A total of 321 293 eligible subjects were identified. Irrespective of the algorithm, sensitivities for defining CKD (eGFR < 60 mL/min/1.73m(2)) using administrative codes were low. A case-definition algorithm employing two physician claims or one hospitalization within a 2-year period had sensitivity of 19.4%, specificity of 97.2%, PPV of 60.1% and NPV of 84.8% for detecting CKD. Estimates of sensitivity were higher when <30 mL/min/1.73m(2) was used as the reference standard, although PPVs were lower and consistently less than 50%. CONCLUSION These results, using eGFR as a reference standard, suggest that administrative data have insufficient sensitivity and PPV for CKD surveillance, although they may be useful when highly specific algorithms are required for research purposes.

Canadian Society of Nephrology Commentary on the 2012 KDIGO Clinical Practice Guideline for Glomerulonephritis: Management of Nephrotic Syndrome in Children

The KDIGO (Kidney Disease: Improving Global Outcomes) clinical practice guideline for management of glomerulonephritis was recently released. The Canadian Society of Nephrology convened a working group to review the recommendations and comment on their relevancy and applicability to the Canadian context. A subgroup of pediatric nephrologists reviewed the guideline statements for management of childhood nephrotic syndrome and agreed with most of the guideline statements developed by KDIGO. This commentary highlights areas in which there is lack of evidence and areas in need of translation of evidence into clinical practice. Areas of controversy or uncertainty, including the length of corticosteroid therapy for the initial presentation and relapses, definitions of steroid resistance, and choice of second-line agents, are discussed in more detail. Existing practice variation is also addressed.

Associations Between Hydration Status, Intravenous Fluid Administration, and Outcomes of Patients Infected With Shiga Toxin–Producing Escherichia coli: A Systematic Review and Meta-analysis

Importance The associations between hydration status, intravenous fluid administration, and outcomes of patients infected with Shiga toxin–producing Escherichia coli (STEC) remain unclear. Objective To determine the relationship between hydration status, the development and severity of hemolytic uremic syndrome (HUS), and adverse outcomes in STEC-infected individuals. Data Sources MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials via the OvidSP platform, PubMed via the National Library of Medicine, CINAHL Plus with full text, Scopus, Web of Science, ClinicalTrials.gov, reference lists, and gray literature were systematically searched. Study Selection Two reviewers independently identified studies that included patients with hydration status documentation, proven or presumed STEC infection, and some form of HUS that developed. No language restrictions were applied. Data Extraction and Synthesis Two reviewers independently extracted individual study data, including study characteristics, population, and outcomes. Risk of bias was assessed using the Newcastle-Ottawa Scale; strength of evidence was adjudicated using the Grading of Recommendations Assessment, Development, and Evaluation method. Meta-analyses were conducted using random-effects models. Main Outcomes and Measures Development of HUS, complications (ie, oligoanuric renal failure, involvement of the central nervous system, or death), and interventions (ie, renal replacement therapy). Results Eight studies comprising 1511 patients (all children) met eligibility criteria. Unpublished data were provided by the authors of 7 published reports. The median risk-of-bias score was 7.5 (range, 6-9). No studies evaluated the effect of hydration during STEC infections on the risk for HUS. A hematocrit value greater than 23% as a measure of hydration status at presentation with HUS was associated with the development of oligoanuric HUS (OR, 2.38 [95% CI, 1.30-4.35]; I2 = 2%), renal replacement therapy (OR, 1.90 [95% CI, 1.25-2.90]; I2 = 17%), and death (OR, 5.13 [95% CI, 1.50-17.57]; I2 = 55%). Compared with putatively hydrated patients, clinically dehydrated patients had an OR of death of 3.71 (95% CI, 1.25-11.03; I2 = 0%). Intravenous fluid administration up to the day of HUS diagnosis was associated with a decreased risk of renal replacement therapy (OR, 0.26 [95% CI, 0.11-0.60]). Conclusions and Relevance Two predictors of poor outcomes for STEC-infected children were identified: (1) the lack of intravenous fluid administration prior to establishment of HUS and (2) a higher hematocrit value at presentation. These findings point to an association between dehydration and adverse outcomes for children with HUS.