Prescribing Quality and Prediction of Clinical Outcomes in Patients With Type 2 Diabetes: A Prospective Cohort Study

Prescribing quality indicators (PQIs) are used to assess whether patients are treated according to guideline recommendations. To ensure that the use of PQIs leads to improved patient outcomes, their predictive validity needs to be assessed (1). We assessed whether newly developed PQIs for diabetes care are associated with better intermediate cardiometabolic and renal outcomes in patients with type 2 diabetes. Special focus was on clinical action indicators that consider patients with elevated risk factor levels to be receiving adequate treatment when treatment is either started or intensified or when they return to control (2). Such indicators are considered more meaningful and fair than presently used indicators that focus on current medication use or on achieving risk factor control (3).

A cohort study was conducted using data from the Groningen Initiative to Analyze Type 2 Diabetes Treatment (GIANTT) database, including medical records data of 26,321 patients with type 2 diabetes in primary care. Eleven previously developed and validated PQIs measuring prescribing of glucose-lowering drugs, statins, antihypertensives, and renin-angiotensin-aldosterone system (RAAS) blockers were evaluated (4). Associations were tested between receipt of the recommended treatment in 2012, as measured by each PQI, and the related outcome (reduction in HbA_1c, LDL cholesterol, systolic blood pressure [SBP], or albuminuria) the following year. We used regression models, adjusted for baseline values.

At baseline, patients were on average 66.8 years old and 50.7% were female, with a median diabetes duration of 5 years. Mean HbA_1c was 6.9% (52.0 mmol/mol), mean LDL cholesterol was 2.61 mmol/L, mean SBP was 140.5 mmHg, and 12.4% of patients had micro- or macroalbuminuria. Of all patients, 77% received glucose-lowering drugs, 67% received statins, and 76% received antihypertensives. All eight clinical action indicators focusing on start or intensification of glucose-lowering drugs, statins, antihypertensives, and RAAS blockers were significantly associated with relevant changes in HbA_1c, LDL cholesterol, SBP, or albuminuria, respectively (Fig. 1). In addition, the indicator assessing current use of statins was associated with a small LDL cholesterol decrease, while the two indicators on current use of RAAS blockers were not associated with a lower risk of albuminuria (Fig. 1).

This is a first study testing the predictive validity of a set of clinical action indicators that were developed using a systematic structured approach (4). The results are in line with previous findings, showing that these PQIs are predictive of better intermediate outcomes (5). Future research should focus on associations with hard outcomes to confirm the predictive validity. The studied population was relatively well controlled, which could limit significant improvements. The clinical action indicators, however, focus on patients with elevated risk factor levels. Therefore, we expect that the results will be comparable in less well-controlled populations.

In conclusion, all eight clinical action indicators on timely start and intensification of glucose-lowering drugs, statins, antihypertensives, and RAAS blockers and one current use indicator on statins are predictive of better intermediate patient outcomes. These indicators can therefore be used for quality assessment and benchmarking purposes. The current use indicators on RAAS blockers were not associated with intermediate patient outcomes and need further evaluation or adaption.