title: The impact of cost-sharing schemes on drug compliance in Italy: evidence based on quantile regression.
abstract: OBJECTIVE
  In this article we investigate the causal effect of cost-sharing schemes on compliance with statins in a quantile regression framework.
  
  
  METHODS
  We use the health search CSD-LPD data, a longitudinal observational dataset containing computer-based patient records collected by Italian general practitioners. We exploit a series of natural experiments referring to several introductions of co-payment schemes in some of the Italian regions between 2000 and 2009. We adopt an extended difference-in-differences approach to provide quantile estimates of the impact of co-payments on compliance.
  
  
  RESULTS
  We find that (i) introduction of co-payments hurts residents of regions with worse quality and provision of health care; (ii) within these regions, co-payments were particularly harmful for high compliers; (iii) gender, clinical history and geographic residence are important determinants of compliance among poor compliers; (iv) compliance decreases with the potency and dosage of statins, particularly for poor compliers.
  
  
  CONCLUSIONS
  In the presence of inefficient health-care provision, co-payments are harmful for drug compliance, and this is especially true for patients who are originally good compliers.
authors: Department of Economics and Finance, University of Rome Tor Vergata, CHP PCOR Stanford University, Via Columbia, 2, 00133, Rome, Italy, atella@uniroma2.it.
authors: Vincenzo
authors: V
authors: Atella
authors: Joanna Aleksandra
authors: JA
authors: Kopinska
mesh_terms: D017047:Cost Sharing; D016208:Databases, Factual; D005260:Female; D006801:Humans; D019458:Insurance Coverage / Q000191:economics; D007348:Insurance, Health / Q000191:economics; D007558:Italy; D008137:Longitudinal Studies; D008297:Male; D055118:Medication Adherence; D012044:Regression Analysis