Persistent postoperative pain after inguinal hernia repair in relation to occupational lifting and standing/walking: a 6-month follow-up study.

OBJECTIVES: This study aims to evaluate the risk of persistent postoperative pain after inguinal hernia repair in relation to occupational lifting and standing/walking. METHODS: We conducted a 6-month follow-up study that included all men with an inguinal hernia repair registered in the Danish Hernia Database from 1 January 2015 to 31 October 2016, who were born from 1 October 1949 to 1 October 1998, and who were alive, living in Denmark, and active in the labour market in the week before surgery. Members of the cohort received a questionnaire 6 months after surgery. Exposure estimates were allocated by combining self reported job titles with a job exposure matrix. Prevalence ratios of persistent postoperative pain during activity ≥2 on a numerical rating scale (range 0-10) according to occupational lifting and standing/walking were estimated using Poisson regression. RESULTS: Of 4817 eligible patients, 2609 (54%) returned the questionnaire and 2508 contributed to the analyses. A total of 473 men (18.9%) reported persistent postoperative pain. In the group lifting >1000 to 6125 kg/day, the prevalence was 26.8% compared with 17.5% in the minimally exposed group; adjusted prevalence ratio: 1.44 (95% CI 1.16 to 1.79). For standing/walking >6 hours/day, the prevalence was 23.6% compared with 17.0% in the group standing <4 hours/day; adjusted prevalence ratio: 1.18 (95% CI 0.92 to 1.50). CONCLUSIONS: The risk of persistent postoperative pain after inguinal hernia repair was elevated among men with occupational lifting exposures >1000 kg/day. This finding suggests a preventive potential.

Inguinal hernia repair among men in relation to occupational mechanical exposures and lifestyle factors: a longitudinal study.

OBJECTIVES: To evaluate exposure-response relationships between occupational mechanical exposures and first-time lateral and medial inguinal hernia repair and effects of lifestyle factors. To estimate if occupational mechanical exposures advance the repairs. METHODS: This longitudinal study was based on a cohort of men aged 18-65 years with questionnaire data from the Musculoskeletal Research Database at the Danish Ramazzini Centre. We estimated occupational mechanical exposures using a job exposure matrix. First-time inguinal hernia repairs from 1998 to 2014 were identified in the Danish Hernia Database. We used Cox regression analyses and calculated excess fractions among the exposed and rate advancement periods (RAPs). RESULTS: Among 17 967 men, we identified 382 lateral and 314 medial repairs. The risk of lateral repairs increased with time spent standing/walking with an HR of 1.45 (95% CI 1.12 to 1.88) for ≥6 hours/day versus <4 hours/day, corresponding to an excess fraction of cases of 31% in the group with ≥6 hours/day. This group had a RAP of 6.7 (95% CI 2.6 to 10.8) years. Medial repairs were not associated with occupational mechanical exposures. A body mass index ≥30 kg/m2 showed lower HRs for both repair types. Leisure-time physical activity and smoking status were not related to any of the outcomes. CONCLUSIONS: Assuming a causal relationship, the results suggest that around 30% of all first-time lateral inguinal hernia repairs in the highest exposure category would be preventable if the time spent standing/walking could be reduced from ≥6 to <4 hours/day. The repairs might even be postponed by 6-7 years.

Risk and prognosis of inguinal hernia in relation to occupational mechanical exposures--a systematic review of the epidemiologic evidence.

OBJECTIVES: 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.

Impact of occupational mechanical exposures on risk of lateral and medial inguinal hernia requiring surgical repair.

OBJECTIVES: We undertook a register-based cohort study to evaluate exposure-response relations between cumulative occupational mechanical exposures, and risk of lateral and medial inguinal hernia repair. METHODS: Among all men born in Denmark between 1938 and 1988, we established a cohort comprising those aged 18-65 years of age, who had at least 1 year of full-time employment between 1993 and 2007. Using information from a Job Exposure Matrix based on expert judgement and year-by-year information on Danish International Standard Classification of Occupations codes for each individual since 1993, we established time-varying cumulative estimates of exposure to daily lifting activities and standing/walking. Cumulative exposures for lagged 5-year time windows were expressed in a way that corresponds to the pack-year concept of smoking (ton-years, frequent-heavy-lifting years, and standing-years). First-time inguinal hernia repairs in the period 1998-2008 were identified in the Danish Hernia Database. We used a logistic regression technique equivalent to survival analysis, adjusting for age, socioeconomic status, region of residence and calendar year. RESULTS: Within the cohort of 1 545 987 men, we identified 22 926 lateral, 15 877 medial and 1592 pantaloon or unspecified first-time inguinal hernia repairs. The risk of lateral hernia repair increased with ton-years, frequent-heavy-lifting-years, and standing-years, with ORs of up to around 1.4. The exposures correlated, but standing-years remained as the most robust risk factor after adjustment for lifting exposures. In general, the risk of medial hernia repair was unrelated to the exposures. CONCLUSIONS: Our findings suggest an increased risk of lateral inguinal hernia repair in relation to occupational mechanical exposures and a preventive potential of around 15% of all cases.