Follow-up of the WHO Multinational Study of Vascular Disease in Diabetes: general description and morbidity.

The incidence of retinal, renal and cardiovascular complications and their relation to baseline risk factors was documented in this follow-up study of 10 of the 14 original centres of the WHO Multinational Study of Vascular Disease in Diabetes (WHO MSVDD). The incidence of specified items of vascular disease and some associated risk factors was ascertained after 7 to 9 years (11-12 years in Oklahoma, USA) follow-up, re-using baseline examination methodology in 3165 patients (66.9 %) and, through secondary information in 717 (15.2%) of the 4729 original patients, of whom 540 (11.4%) had died and 307 (6.5 %) were untraceable. During follow-up, approximately one third of the patients developed hypertension and one third started insulin. Coronary heart disease incidence varied 10 to 20-fold among centres as did limb amputation rates. Inter-centre differences in incident retinopathy and severe visual impairment were smaller but incident clinical proteinuria and renal failure varied markedly. Vascular disease incidence of all categories was high in Native Americans though coronary heart disease incidence was relatively low in Pima Indians and absolutely low in Hong Kong and Tokyo patients. Specific vascular events and their relation with baseline risk factors are analysed in accompanying papers, summarised in the Epilogue. These 10 centres reported very different incidence rates of vascular complications. Observer variation, selection biases and competing causes of mortality contributed to these differences but their validity is supported by the more objective outcome indicators. The following papers also suggest that baseline factors such as raised arterial pressure, cholesterol and fasting glucose (in the centres where it was measured) were important and potentially reversible predictors of risk.