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Bias and Power in Group-Based Epidemiologic Studies of Low-Back Pain Exposure and Outcome - Effects of Study Size and Exposure Measurement Efforts

Authors :
Idsart Kingma
Svend Erik Mathiassen
Pieter Coenen
Paulien M Bongers
J.H. van Dieen
Cécile R. L. Boot
Kinesiology
EMGO+ - Musculoskeletal Health
Research Institute MOVE
Public and occupational health
EMGO - Musculoskeletal health
MOVE Research Institute
Source :
Annals of Occupational Hygiene, 59(4), 439-454. Oxford University Press, Coenen, P, Mathiassen, S E, Kingma, I, Boot, C R, Bongers, P M & van Dieen, J H 2015, ' Bias and Power in Group-Based Epidemiologic Studies of Low-Back Pain Exposure and Outcome-Effects of Study Size and Exposure Measurement Efforts. ', Annals of Occupational Hygiene, vol. 59, no. 4, pp. 439-454 . https://doi.org/10.1093/annhyg/meu102, Annals of Occupational Hygiene, 4, 59, 439-454
Publication Year :
2015

Abstract

Objectives: Exposure-outcome studies, for instance on work-related low-back pain (LBP), often classify workers into groups for which exposures are estimated from measurements on a sample of workers within or outside the specific study. The present study investigated the influence on bias and power in exposure-outcome associations of the sizes of the total study population and the sample used to estimate exposures. Methods: At baseline, lifting, trunk flexion, and trunk rotation were observed for 371 of 1131 workers allocated to 19 a-priori defined occupational groups. LBP (dichotomous) was reported by all workers during 3 years of follow-up. All three exposures were associated with LBP in this parent study (P < 0.01). All 21 combinations of n = 10, 20, 30 workers per group with an outcome, and k = 1, 2, 3, 5, 10, 15, 20 workers actually being observed were investigated using bootstrapping, repeating each combination 10000 times. Odds ratios (OR) with P values were determined for each of these virtual studies. Average OR and statistical power (P < 0.05 and P < 0.01) was determined from the bootstrap distributions at each (n, k) combination. Results: For lifting and flexed trunk, studies including n ≥ 20 workers, with k ≥ 5 observed, led to an almost unbiased OR and a power >0.80 (P level = 0.05). A similar performance required n ≥ 30 workers for rotated trunk. Small numbers of observed workers (k) resulted in biased OR, while power was, in general, more sensitive to the total number of workers (n). Conclusions: In epidemiologic studies using a group-based exposure assessment strategy, statistical performance may be sufficient if outcome is obtained from a reasonably large number of workers, even if exposure is estimated from only few workers per group. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Details

Language :
English
ISSN :
00034878
Volume :
59
Issue :
4
Database :
OpenAIRE
Journal :
Annals of Occupational Hygiene
Accession number :
edsair.doi.dedup.....22648ce8eb74203af4ea95d1730d5c18
Full Text :
https://doi.org/10.1093/annhyg/meu102