BMJ  2003;326:1265 (7 June), doi:10.1136/bmj.326.7401.1265

Letter

Mortality associated with foodborne bacterial gastrointestinal infections

Statistical method is worth examining

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

EDITOR—Helms et al report a significant association between common foodborne infections, including campylobacteriosis, and increased short term and long term mortality.1 As this conflicts with conventional clinical wisdom,2 it is worth scrutinising the statistical method supporting the claim.

Helms et al compare ill cases with healthier (general population) controls by using a comorbidity index to adjust for the fact that underlying conditions were more common among patients than in the control group, particularly AIDS related illness, metastatic cancers, and lymphomas or leukaemia. But even after adjusting for comorbidity, the relative mortality fell only from 3.10 to 2.56.

Both the small impact of comorbidity adjustment and the association between infections and morbidity can be explained by known limitations of the Charlson comorbidity index. For example, for lung cancer survival, the Charlson index explained only 2.0% of the variation in survival.3 It has not been validated for gastrointestinal infections in . . . [Full text of this article]

Louis Anthony Cox, Jr, president

Cox Associates, 503 Franklin Street, Denver, CO 80218, USA


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to StumbleUpon StumbleUpon   Add to Technorati Technorati    What's this?

Relevant Article

Short and long term mortality associated with foodborne bacterial gastrointestinal infections: registry based study • Commentary: matched cohorts can be useful
Morten Helms, Pernille Vastrup, Peter Gerner-Smidt, Kåre Mølbak, and Stephen Evans
BMJ 2003 326: 357. [Abstract] [Full Text] [PDF]

Access jobs at BMJ Careers
Whats new online at Student BMJ