Risk and prognosis of inguinal hernia in relation to occupational mechanical exposures--a systematic review of the epidemiologic evidence.
OBJECTIVE
The aim of this review was to evaluate the epidemiologic evidence for (i) a causal effect of         occupational mechanical exposures on incidence of inguinal hernia, and (ii) a prognostic effect of such exposures on         hernia recurrence and persistent pain after inguinal hernia repair.


METHODS
We performed a literature search in         Medline, Embase, and Web of Science up to 3 November 2011. Central information was extracted from included studies, and         strengths and limitations were discussed.


RESULTS
All 23 included studies focused on effects of (work) activities that         hardly reflected specific occupational risk factors. Eight studies provided information on risk by occupation or         occupational activities. Increased risk was reported in six studies, but inflationary bias was likely. The negative         findings in two studies might well be explained by bias towards the null due to crude exposure and/or outcome         assessment. Three studies on single strenuous events primarily reflected patients` beliefs regarding risk factors.         Information on prognosis with respect to recurrence was found in seven studies. The studies used crude exposure         assessment, and two were also underpowered. Four suggested an increased risk. Six studies on prognosis with respect to         persistent pain (one of which also concerned recurrence) were practically non-informative for the purpose of this         review.


CONCLUSIONS
There is insufficient epidemiologic evidence to draw meaningful conclusions about (i) the         existence of causal associations between specific occupational mechanical exposures and the development of inguinal         hernia, and (ii) the influence of these exposures on prognosis after inguinal hernia repair with respect to hernia         recurrence and persistent pain.
Danish Ramazzini Centre, Department of Occupational Medicine, Herning Regional Hospital, Herning, Denmark. susasven@rm.dk
Susanne Wulff
SW
Svendsen
Poul
P
Frost
Marie Vestergaard
MV
Vad
Johan Hviid
JH
Andersen
D006552:Hernia, Inguinal / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D006801:Humans; D015994:Incidence; D017770:Lifting; D009784:Occupational Diseases / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D016273:Occupational Exposure / Q000009:adverse effects*; D016272:Occupational Health; D009790:Occupations; D015995:Prevalence; D011379:Prognosis; D012008:Recurrence; D012307:Risk Factors; D013312:Stress, Physiological