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Author's reply - Risk of bias

Posted by chodick on 13 Dec 2013 at 15:47 GMT

We thank the author for his/her comment. Smoking is indeed a potential confounder in this study. As the author points out, a recently published study has shown that adherent statins users are approximately 10% less likely to be smokers (1). However, a sensitivity analysis assuming that smoking is associated with a relative risk of 2.6 for rheumatoid arthritis (RA) (2) and that the relevant age-specific prevalence of smoking in Israel is approximately 11% (3), indicate that our study results would change only mildly after adjusting for smoking. For example, the hazard ratio for RA calculated for patients with proportion of days covered with statins of 80% or more would change from 0.69 (95% confidence interval: 0.57-0.83) to 0.71 (95%CI: 0.59-0.86). The results of the recent study do not suggest that alcohol consumption is related with adherence with statins.


References
1. Warren JR, Falster MO, Fox D, Jorm L. Factors influencing adherence in long-term use of statins. Pharmacoepidemiol Drug Saf. 2013 Dec;22(12):1298-307.
2. Heliövaara M, Aho K, Aromaa A, Knekt P, Reunanen A. Smoking and risk of rheumatoid arthritis. The Journal of Rheumatology [1993, 20(11):1830-1835]
3. Israel Ministry of Health, Smoking Status in Israel 2012, http://www.health.gov.il/....

No competing interests declared.