Diabetes in urban African-Americans. XIX. Prediction of the need for pharmacological therapy

OBJECTIVE - To develop a prediction rule that will identify patients who wi ll require pharmacological therapy within 6 months of first presentation to a diabetes clinic. RESEARCH DESIGN AND METHODS - Among the patients who came to the Grady Diab etes Clinic between 1991 and 1997, we randomized 557 frequent attenders to a development group and 520 frequent attenders to a validation group. Using multiple logistical regression, we derived a prediction rule in the develo pment group to project whether patients would require pharmacological inter vention to achieve HbA(1c) levels <7% after 6 months. The utility of the pr ediction rule was then confirmed in the validation group and tested prospec tively on an additional group of 93 patients who presented from 1997 to 199 8. Performance of the pre diction rule was assessed using receiver operatin g characteristic (ROC) curves. RESULTS- The rule (-4.469 + 1.932 x sulfonylurea Rx + 1.334 x insulin Rx 0.196 x duration + 0.468 x fasting glucose, where "Rx" indicates a prescrip tion) predicted the need for pharmacological intervention in the developmen t group (P < 0.0001). Use of insulin or sulfonylurea therapy at presentatio n, duration of diabetes. and fasting glucose levels were significant predic tors of the future need for pharmacological management. The prediction rule also performed well in the validation group (positive predictive value 90% , correlation between predicted and observed need for medical management 0. 99). ROC curves confirmed the value of the prediction rule (area under the curves was 0.91 for the development group, 0.85 for the validation group, a nd 0.81 for the prospective group). CONCLUSIONS - Early identification of individuals who will require pharmaco logical intervention to achieve national standards for glycemic control can be achieved with high probability, thus allowing for more efficient manage ment of diabetes.