Suggestions for STROBE recommendations.

The STROBE initiative is an excellent approach to improving observational epidemiologic studies. Our concerns include: 1) the need for further emphasis on presenting a clear definition of the hypothesis, its biologic rationale, and its implication to the health of the public; 2) correction of the glaring omission in the STROBE guidelines of the necessity to consider the incubation periods for risk factors and diseases and to review other biologically relevant issues that often have a major impact on the plausibility of the observed association; 3) the essential importance of guidance about a careful definition of host factors, including a clear statement of results specific to race, sex and ethnicity rather than merely stating: "The interaction term was not significant"; 4) the importance of specifying that all studies should present the actual rates or numbers of events in relation to the size of the population, including the actual numbers for each independent variable in a multiple regression analysis, rather than solely presenting a hazards ratio; and 5) the need to restrict the P value only to those hypotheses that were generated prior to the data analysis, reserving retrospective analyses to point estimates and confidence limits.