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The composition of the patient population influences indicators scores for the quality of diabetes care in general practice.

Nielen, M., Korevaar, J., Stirbu-Wagner, I., Verheij, R. The composition of the patient population influences indicators scores for the quality of diabetes care in general practice.: , 2014.
Objective: Indicator scores are increasingly used to compare quality of care for diabetes patients etween general practices. Patient characteristics, such as age, gender and presence of other chronic diseases, are known to be associated with the care process. We studied to which extent patient characteristics influence quality indicator scores for diabetes care at general practice level. Methods: We included 10,832 patients with diabetes mellitus from 62 general practices participating in NIVEL’s Primary Care Database in 2011. A set of 14 quality indicators was used including both process and intermediate outcome scores; i.e. HbA1c, blood pressure, LDL cholesterol, total cholesterol, body mass index, kidney function and smoking status. Based on multilevel logistic regression models we assessed the variation of quality indicator scores between practices with and without taking patient characteristics (age, gender and comorbidity) into account. Per practice, it was determined whether or not corrections for patient characteristics (case-mix correction) resulted in a relevant change of indicator scores (>2% decrease or increase of the indicator score at practice level). Results: Corrections for patient characteristics did not significantly reduce the over-all variation of indicator scores between general practices. However, for individual practices, correction for case-mix resulted in relevant changes. In 18% - 45% (median 26%) of the practices, case-mix correction resulted in a change of process indicator scores of more than 2%. For example, the largest increase for the HbA1c process indicator score in a practice was 5.7% (increase from 72.3% to 78.1%). For the intermediate outcome indicators, 34% - 66% (median 52%) of the practices had a relevant change in indicator scores. For example, for systolic blood pressure the largest increase of the intermediate outcome indicator score in a practice was 9.9% (increase from 32.1% to 42.1%). Conclusions: At general practice level, indicator scores for the quality of diabetes care are influenced by characteristics of the patient population. For a fair and valid comparison of scores between general practices, a correction for the composition of the patient population is necessary. (aut. ref.)