More evidence to support the "healthy adherer" effect
A meta-analysis in the July 1st issue of the British Medical Journal provides additional evidence to support the existence of a "healthy adherer" effect, i.e. individuals who adhere to treatment in clinical research have improved mortality/morbidity as compared with non-adherers, even if they're only receiving a placebo therapy. The authors further note, "...adherence to drug therapy may be a surrogate marker for overall healthy behaviour."
The meta-analysis included 21 studies representing a total of 46,847 participants.
Excerpt from the abstract: "Compared with poor adherence, good adherence was associated with lower mortality (odds ratio 0.56, 95% confidence interval 0.50 to 0.63). Good adherence to placebo was associated with lower mortality (0.56, 0.43 to 0.74), as was good adherence to beneficial drug therapy (0.55, 0.49 to 0.62). Good adherence to harmful drug therapy was associated with increased mortality (2.90, 1.04 to 8.11)."
Reference: Simpson SH, Eurich DT, Majumdar SR, Padwal RS, Tsuyuki RT, Varney J, Johnson JA. A meta-analysis of the association between adherence to drug therapy and mortality. BMJ. 2006 Jul 1;333(7557):15.