Editor—The article by Wennberg et al on variation in the use of healthcare resources at the end of life raises several questions.1
It implies that the frequency of use of services is associated with workforce supply, but other studies contradict this. Supplier induced demand does not explain doctor variability in Norway,2 and economists have noted the methodological difficulty of making interpretations about supplier induced demand.3 Variability is still a major phenomenon in countries with centrally planned health systems which have less scope for inducement, such as the NHS in the United Kingdom. There is a fine interpretative line between healthcare activity that is induced by supply and healthcare activity that varies because some patients face inequitable barriers to access. Even if inducement is an issue in the United States, this interpretation may not be generalisable to other countries, given the market orientation of aspects of healthcare there.
The claim that greater use is associated with worse outcomes, making variability a direct risk to patient, requires caution. Given the difficulty, and perhaps even the theoretical impossibility,4 of establishing a single “correct” population rate of use for a healthcare intervention, it is difficult to interpret doctor variation as inherently bad. If it is not possible to say what the single, best, population rate of treatment should be, why should we expect clinicians not to vary in their practice when observed across populations?
The results presented in this paper are interesting, but their interpretation is very complex and should be treated with caution,5 especially when trying to generalise to settings outside the United States.
Competing interests: None declared.
References
- 1.Wennberg JE, Fisher ES, Stukel TA, Skinner JS, Sharp SM, Bronner KK. Use of hospitals, physician visits, and hospice care during the last six months of life among cohorts loyal to highly respected hospitals in the United States. BMJ 2004;328: 607. (13 March.) [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Grytten J, Sorensen R. Type of contract and supplier-induced demand for primary physicians in Norway. J Health Econ 2001;20: 379-93. [DOI] [PubMed] [Google Scholar]
- 3.Folland S, Stano M. Small area variations: a critical review of propositions, methods, and evidence. Med Care Rev 1990;47: 419-65. [DOI] [PubMed] [Google Scholar]
- 4.Tanenbaum SJ. Evidence and expertise: the challenge of the outcomes movement to medical professionalism. Acad Med 1999;74: 757-63. [DOI] [PubMed] [Google Scholar]
- 5.Lilford R, Mohammed AM, Spiegelhalter D, Thomson R. Use and misuse of process and outcome data in managing performance of acute medical care: avoiding institutional stigma. Lancet 2004;363: 1147-54. [DOI] [PubMed] [Google Scholar]