Objectives Inverse probability of treatment weighting (IPTW) has been used in observational studies to reduce selection bias. To obtain estimates of the main effects, a pseudo data set is created by weighting each subject by IPTW and analyzed with conventional regression models. Currently variance estimation requires additional work depending on type of outcomes. Our goal is to demonstrate a statistical approach to directly obtain appropriate estimates of variance of the main effects in regression models. Methods We carried out theoretical and simulation studies to show that the variance of the main effects estimated directly from regressions using IPTW is underestimated, and that the type I error rate is higher due to the inflated sample size in the pseudo data. The robust variance estimator using IPTW often slightly overestimates the variance of the main effects. We propose to use the stabilized weights to directly estimate both the main effect and its variance from conventional regression models. Results We applied the approach to a study examining the effectiveness of serum potassium monitoring in reducing hyperkalemia-associated adverse events among 27,355 diabetic patients newly-prescribed a renin-angiotensin-aldosterone system (RAAS) inhibitor. The incidence rate ratio (with monitoring versus without monitoring) and confidence intervals were 0.46 (0.34, 0.61) using the stabilized weights compared to 0.46 (0.38, 0.55) using typical inverse probability of treatment weighting. Conclusions Our theoretical, simulation results and real data example demonstrate that the use of the stabilized weights in the pseudo data preserves the sample size of the original data, produces appropriate estimation of the variance of main effect, and maintains an appropriate type I error rate.

OBJECTIVE -The goal of this study was to examine whether maternal dietary intake of vitamin D, -3 fatty acids, and -6 fatty acids during pregnancy is associated with the appearance of islet autoimmunity (IA) in offspring. RESEARCH DESIGN AND METHODS -The Diabetes Autoimmunity Study in theYoung (DAISY) is recruiting at birth and following children at increased risk for type 1 diabetes, as determined by HLA-DR genotype or by family history of type 1 diabetes. A total of 233 mothers of newly recruited DAISY subjects were asked to recall their intake of food and nutritional supplements during the third trimester of pregnancy using the Willett food frequency questionnaire. Children were followed for an average of 4 years (range 0.8 -7.3 years) for the appearance of insulin, GAD 65 , and IA-2 autoantibodies. Sixteen children developed at least one autoantibody during this period. Unadjusted and adjusted hazard ratios (HRs) for the development of IA were estimated with survival analysis using a Weibull distribution.RESULTS -Maternal intake of vitamin D via food was significantly associated with a decreased risk of IA appearance in offspring, independent of HLA genotype, family history of type 1 diabetes, presence of gestational diabetes mellitus, and ethnicity (adjusted HR ϭ 0.37; 95% CI 0.17-0.78). Vitamin D intake via supplements, -3 fatty acids, and -6 fatty acids intake during pregnancy were not associated with appearance of IA in offspring.CONCLUSIONS -Our findings suggest that maternal intake of vitamin D through food during pregnancy may have a protective effect on the appearance of IA in offspring. Diabetes Care 26:3237-3242, 2003T ype 1 diabetes is a T-cell-mediated autoimmune disease characterized by the destruction of insulinproducing ␤-cells of the pancreas. The causes of type 1 diabetes are unknown, yet low concordance rates among monozygotic twins (1), a 10% progression rate among those genetically susceptible (2), migratory studies (3), and increasing worldwide incidence rates (4) suggest that genetic factors interact with environmental factors in the development of type 1 diabetes. These environmental factors have not been clearly identified.Type 1 diabetes is preceded by a preclinical stage termed islet autoimmunity (IA) that signals the beginning of ␤-cell destruction with the presence of autoantibodies against islet autoantigens. IA appears typically by 2 years of age and sometimes as early as 3 months of age in individuals with type 1 diabetic firstdegree relatives (5-7). Autoantibodies can be persistent for months or years, often predicting clinical diagnosis, or can be transient. Transient autoantibody positivity has not been associated with genetic risk factors (7,8), suggesting that environmental factors may be involved in suppressing persistent ␤-cell destruction.Increased expression of proinflammatory cytokines may be associated with the appearance and persistence of IA (9). Vitamin D and the -3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to modify th...

Having online access to medical records and clinicians was associated with increased use of clinical services compared with group members who did not have online access.

SummaryBackground and objectives A multidisciplinary team (MDT) approach to chronic kidney disease (CKD) may help optimize care of CKD and comorbidities. We implemented an MDT quality improvement project for persons with stage 3 CKD and comorbid diabetes and/or hypertension. Our objective was to decrease the rate of decline of GFR.Design, setting, participants, & measurements We used a 4-year historical cohort to compare 1769 persons referred for usual nephrology care versus 233 referred for MDT care within an integrated, not-for-profit Health Maintenance Organization (HMO). Usual care consisted of referral to an outside nephrologist. The MDT consisted of an HMO-based nephrologist, pharmacy specialist, diabetes educator, dietitian, social worker, and nephrology nurse. Both groups received usual primary care. The primary outcome was rate of decline of GFR. Secondary outcomes were LDL, hemoglobin A1c, and BP.Results In multivariate repeated-measures analyses, MDT care was associated with a mean annual decline in GFR of 1.2 versus 2.5 ml/min per 1.73 m 2 for usual care. In stratified analyses, the significant difference in GFR decline persisted only in those who completed their referrals. There were no differences in the secondary outcomes between groups. ConclusionsIn this integrated care setting, MDT care resulted in a slower decline in GFR than usual care. This occurred despite a lack of significant differences for secondary disease-specific measures, suggesting that other differences in the MDT population or care process accounted for the slower decline in GFR in the MDT group.

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