BMJ  2006;333:1124 (25 November), doi:10.1136/bmj.39038.515521.1F

Letters

Statins and outcomes in patients with pneumonia

Appreciating bias and precision in study

The first 150 words of the full text of this article appear below.

The work by Majumdar et al is a major step forwards in dealing with confounding of uncertain direction and magnitude in studying pleiotropic effects of statins.¹ However, we believe that despite the limited statistical power of the study, the investigators should have planned subgroup analyses for institutionalised and non-institutionalised patients separately as, for example, in influenza vaccine studies. When examining table 1 it becomes clear that 20% of the non-statin users and only 8% of the statin users were nursing home residents (P<0.001).

Nursing home residents have other risk profiles than community dwelling people, and uptake of medication is determined by many factors other than their absolute risk of outcome. Importantly, in-hospital treatment may also be different for the separate groups. Including such a subgroup of study subjects may therefore distort the association under study in such a way that confounding cannot be effectively controlled for or, even worse, more . . . [Full text of this article]

¹ University Medical Center Utrecht, PO Box 85060, 3508 GA, Utrecht, Netherlands

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Relevant Article

Statins and outcomes in patients admitted to hospital with community acquired pneumonia: population based prospective cohort study

Sumit R Majumdar, Finlay A McAlister, Dean T Eurich, Raj S Padwal, and Thomas J Marrie
BMJ 2006 333: 999. [Abstract] [Full Text] [PDF]