Association of practice size and pay-for-performance incentives with the quality of diabetes management in primary care

Background:

Not enough is known about the association between practice size and clinical outcomes in primary care. We examined this association between 1997 and 2005, in addition to the impact of the Quality and Outcomes Framework, a pay-for-performance incentive scheme introduced in the United Kingdom in 2004, on diabetes management.

Methods:

We conducted a retrospective open-cohort study using data from the General Practice Research Database. We enrolled 422 general practices providing care for 154 945 patients with diabetes. Our primary outcome measures were the achievement of national treatment targets for blood pressure, glycated hemoglobin (HbA_1c) levels and total cholesterol.

Results:

We saw improvements in the recording of process of care measures, prescribing and achieving intermediate outcomes in all practice sizes during the study period. We saw improvement in reaching national targets after the introduction of the Quality and Outcomes Framework. These improvements significantly exceeded the underlying trends in all practice sizes for achieving targets for cholesterol level and blood pressure, but not for HbA_1c level. In 1997 and 2005, there were no significant differences between the smallest and largest practices in achieving targets for blood pressure (1997 odds ratio [OR] 0.98, 95% confidence interval [CI] 0.82 to 1.16; 2005 OR 0.92, 95% CI 0.80 to 1.06 in 2005), cholesterol level (1997 OR 0.94, 95% CI 0.76 to 1.16; 2005 OR 1.1, 95% CI 0.97 to 1.40) and glycated hemoglobin level (1997 OR 0.79, 95% CI 0.55 to 1.14; 2005 OR 1.05, 95% CI 0.93 to 1.19).

Interpretation:

We found no evidence that size of practice is associated with the quality of diabetes management in primary care. Pay-for-performance programs appear to benefit both large and small practices to a similar extent.There is a well-established body of literature showing positive associations between volume of patients and clinical outcomes in health care, which has been documented by a systematic review.¹ However, this association has usually been examined in a limited number of discrete procedures, and most studies have involved hospital-based services rather than primary care settings.^2–5Improving our understanding of the association between volume of patients and outcomes in primary care is important for several reasons. First, most contacts with health systems occur in primary care settings, and optimizing the delivery of these services has the potential to improve the health of the population.⁶ Second, over the past decade, primary care has assumed greater responsibility for managing the growing burden of chronic disease.^7,8 Larger providers may be better resourced, through the employment of additional support staff and greater use of information technology, to deliver the systematic, structured care necessary for the effective management of chronic disease.^6,9 Third, larger providers may have been more responsive to nonfinancial and financial incentives, including pay for performance, implemented by payers aimed at improving the quality of care.^7,10 Fourth, in many countries, primary care is based around a predominance of small practices.^6,11,12 In 2006, 53% of practices in England and Wales had three or fewer family physicians.¹¹ In the same year in the United States, 30.3% of family physicians were in solo practice; 9.4% were in two-physician practices.¹²Despite the limited data available, concerns have been raised about the standards of care delivered by smaller family practices.¹³ In the United Kingdom and Canada, this has resulted in an explicit policy objective of encouraging smaller practices to amalgamate.^13,14Our study examines the associations between the size of practice and the quality of diabetes management in UK primary care settings between 1997 and 2005. We tested the hypotheses that patients attending larger family practices receive better care for diabetes and that the quality gap between larger and smaller practices has increased over the past decade. We also hypothesized that larger practices derived more benefit from the Quality and Outcomes Framework, a major pay-for-performance program in primary care introduced in 2004.