Construction and validation of a model to predict nonadherence to guidelines for prescribing antiplatelet therapy to hypertensive patients

Objective: To construct and validate a model to predict nonadherence to guidelines for prescribing antiplatelet therapy (NGAT) to hypertensive patients. Methods: This 3 month prospective study was undertaken in 2007-2009 to determine whether 712 hypertensive patients were or were not being prescribed antiplatelet therapy. Outcome: NGAT according to clinical guidelines (just for patients in secondary prevention or with Systematic COronary Risk Evaluation (SCORE) >= 10%). Secondary variables: Duration of hypertension (years), blood pressure (BP), age, gender, smoking, diabetes, dyslipidemia, cardiovascular disease, lipid parameters, SCORE. Of the whole sample 80% was used to construct the model and 20% to validate it. To construct the model, we performed a multivariate logistic regression model which was adapted to be a scoring system with risk groups. The adjusted odds ratios (ORs) were obtained through the model. To validate the model we calculated the area under the ROC curve (AUC) and then compared the expected and the observed NGAT. The final model was adapted for use as a mobile application. Results: NGAT: 18.5%, construction; 17.9%, validation. Factors: higher duration of hypertension diagnosis, higher systolic BP, older age, male gender, smoking, diabetes, dyslipidemia and cardiovascular disease. Validation: AUC = 0.82 (95% CI: 0.74-0.90, p<0.001), with no differences between the observed and the expected NGAT (p = 0.334). Conclusion: A tool was constructed and validated to predict NGAT. The associated factors were related with a greater cardiovascular risk. The scoring system has to be validated in other areas.