The period effect in the prevalence of proliferative diabetic retinopathy, gross proteinuria, and peripheral neuropathy in type 1 diabetes: A longitudinal cohort study.

AIMS:To investigate whether, for a specific duration of type 1 diabetes, there is a significant change in the prevalence of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy in those more recently diagnosed with diabetes (a period effect), in the Wisconsin Epidemiologic Study of Diabetic Retinopathy. Where present, to determine how common risk factors for diabetic complications might be associated with it, and what might be driving it. MATERIALS AND METHODS:Longitudinal cohort study with seven examination phases between 1980 and 2014. Multivariate logistic regression models and ordinal parameterization were used to test for and evaluate any period effect. RESULTS:There is a period effect in the prevalence of gross proteinuria and peripheral neuropathy (decreasing), as seen with proliferative diabetic retinopathy (p < 0.001). Adjusting for changing levels of common risk factors attenuates the period effect, particularly for proliferative diabetic retinopathy. For gross proteinuria and peripheral neuropathy, however there is a persistent period effect in spite of adjusting for the major risk factors. CONCLUSIONS:There are period effects in the prevalence of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy that cannot be fully explained by changes in common risk factors for complications of type 1 diabetes in this cohort. The role of other potential confounders warrants further exploration

Adjusted estimated prevalence of each complication at each study visit.

<p><b>(</b>a) Proliferative diabetic retinopathy–adjusted for duration of diabetes and visit. (b) Proliferative diabetic retinopathy–adjusted for duration of diabetes, visit, glycosylated hemoglobin, and systolic blood pressure. (c) Gross proteinuria—adjusted for duration of diabetes and visit. (d) Gross proteinuria—adjusted for duration of diabetes, visit, glycosylated hemoglobin, mean arterial blood pressure, and sex. (e) Peripheral neuropathy—adjusted for duration of diabetes and visit. (f) Peripheral neuropathy—adjusted for duration of diabetes, visit, glycosylated hemoglobin, sex, and smoking status. Log odds = log [p/(1-p)], i.e. log odds of -0.5 = prevalence of 38%, log odds of -1.0 = prevalence of 27%, log odds of -1.5 = prevalence of 18%, and log odds of -2.0 = prevalence of 12%.</p

Prevalence of proliferative diabetic retinopathy, gross proteinuria, and peripheral neuropathy by diabetes duration and visit.

<p>(a) Prevalence of proliferative diabetic retinopathy. (b) Prevalence of gross proteinuria. (c) Prevalence of peripheral neuropathy.</p

Proportion of potential participants who met inclusion and exclusion criteria, relative to the total number of people seen at each study visit.

<p>Proportion of potential participants who met inclusion and exclusion criteria, relative to the total number of people seen at each study visit.</p

Comparison between base and final models of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy.

<p>Comparison between base and final models of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy.</p

Selected characteristics of the all person-visits with the potential to contribute to the primary analyses and all person-visits with complete data for the final models.

<p>Selected characteristics of the all person-visits with the potential to contribute to the primary analyses and all person-visits with complete data for the final models.</p

Comparison between base and final models of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy when participants on dialysis or with kidney, pancreas or islet cell transplants are included.

<p>Comparison between base and final models of proliferative diabetic retinopathy, gross proteinuria and peripheral neuropathy when participants on dialysis or with kidney, pancreas or islet cell transplants are included.</p

Number of person-visits contributing to each model in the primary analyses, based on availability of data on all of the variables included in each model.

<p>Number of person-visits contributing to each model in the primary analyses, based on availability of data on all of the variables included in each model.</p

Dates of the WESDR examinations and numbers of participants with type 1 diabetes.

<p>Dates of the WESDR examinations and numbers of participants with type 1 diabetes.</p