Examining the Long-Term Spillover Effects of a Pay-For-Performance Program in a Health Care System That Lacks Referral Arrangements

Document Type : Original Article


1 Department of Public Health, College of Medicine, Fu-Jen Catholic University, Taipei, Taiwan

2 Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan

3 Department of Internal Medicine, National Taiwan University, Taipei, Taiwan

4 Population Health Research Center, National Taiwan University, Taipei, Taiwan

5 Institute of Health Policy and Management, College of Public Health, National Taiwan University, Taipei, Taiwan


Several studies have examined the intended effects of pay-for-performance (P4P) programs, yet little is known about the unintended spillover effects of such programs on intermediate clinical outcomes. This study examines the long-term spillover effects of a P4P program for diabetes care.

This study uses a nationwide population-based natural experimental design with a 3-year follow-up period under Taiwan's universal coverage health care system. The intervention group consisted of 7,688 patients who enrolled in the P4P program for diabetes care in 2017 and continuously participated in the program for three years. The comparison group was selected by propensity score matching from patients seen by the same group of physicians. Each patient had four records: one pertaining to one year before the index date of the P4P program and the other three pertaining to follow-ups spanning over the next three years. Generalized estimating equations with difference-in-differences estimations were used to consider the correlation between repeated observations for the same patients and patients within the same matched pairs.

Patients enrolled in the P4P program showed improvements in incentivized intermediate outcomes that persisted over three years, including proper control of glycated hemoglobin and low-density lipoprotein cholesterol. We found a slight positive spillover effect of the P4P program on the control of non-incentivized triglyceride). However, we found no such effects on the non-incentivized high-density lipoprotein cholesterol control.

The P4P program has achieved its primary goal of improving the incentivized intermediate clinical outcomes. The commonality in production among a set of activities is crucial for generating the spillover effects of an incentive program.


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Articles in Press, Accepted Manuscript
Available Online from 02 September 2023
  • Receive Date: 26 July 2022
  • Revise Date: 15 August 2023
  • Accept Date: 30 August 2023
  • First Publish Date: 02 September 2023