Offspring sex ratios of people exposed to dioxin and dioxin-like compounds

Sickness absence in doctorsKivimaki et al 1 undertook research to identify some determinants of sickness absence in Finnish hospital physicians between 1997 and 1998.This was a questionnaire survey sent to 816 physicians and a control group of 542 senior nurses employed in one of 11 hospitals in Finland.Social circumstances, work characteristics, and various measures of health were assessed by questionnaire and employers' registers were used to assess recorded sickness absence.There are some limitations in the study design and subsequent conclusions that are not acknowledged in the text.The response rate from the physicians was a disappointing 55%.Nearly half of the physicians approached did not participate in the study.This could bias the results considerably.The authors state that the response rate obtained in this study corresponds to that obtained in previous research.Seven references are cited as evidence.The response rates of doctors from six of the seven quoted papers are higher than 55% and are as follows: 82% 2 ; 79% and 76% 3 ; 63% 4 ; 78% 5 ; 58% 6 ; and 87%-94%.7 The authors could have cited a further reference 8 that was used later in the paper, but chose not to (response rate 80%).The authors state that the recording of attendance is reliable in the Finnish public sector.This would be a very important factor in the context of this study of sickness absence in hospital physicians.The authors cite two references 9 10 to back up their statement.These two studies both concern local government workers in Raisio, Finland between 1990 and 1995 with the main outcome measure being recorded medically certificated absence held on computer by an occupational health unit.Both of these papers simply state that all sick certificates must be forwarded for recording, but provide no other evidence that the recording of sickness absence is reliable.The possibility that doctors might underreport sickness absence, leading to incomplete recording, is not considered.This could add further bias to the study, thereby affecting the results and conclusions.