Revised NIOSH Lifting Equation - Fundamentals and Assessment Tools for Occupational Ergonomics - page 893

FIGURE 46.11 Modified job analysis worksheet, example 2.

46.8 Validation of the Revised NIOSH Lifting Equation

Several studies have been conducted examining the effectiveness of the revised NIOSH lifting equation to
identify jobs with increased risk of lifting-related low back disorders. Waters et al. (1999) conducted a
cross-sectional study to investigate whether there was a significant relationship between risk of LBP
and exposure to jobs with various LI values. In the study, the 1-yr prevalence of LBP was determined
for workers employed in jobs with varying LI values. Fifty jobs at four industrial sites were evaluated
with the NIOSH lifting equation. A symptom and occupational history questionnaire was administered
to 204 people employed in those lifting jobs and 80 people employed in nonlifting jobs at the four sites.
Jobs were categorized by exposure according to the following LI values: LI 0 (unexposed),

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0.0 3.0. Regression analysis was used to determine

whether there was a correlation between the LI and reported LBP. The authors found that as the LI
increased from 0.0 to 3.0, the odds of LBP increased, with a peak and statistically significant odds ratio
(OR

, LI 1.0, 1.0 , LI 2.0, 2.0 , LI 3.0, and LI .

2.45) occurring in the category of jobs with an LI value between 2.0 and 3.0. For the group of
jobs with an LI value greater than 3.0, the OR value was lower (OR

¼

1.63) than for the 2.0 to 3.0
group and was not statistically different from the nonlifting group, but the authors explained that this
finding was most likely due to a combination of worker selection, a survivor effect, and high turnover
in the higher risk jobs. In a study of worker turnover rates on physically demanding jobs, Lavender
and Marras (1994) showed that high turnover rate was a good indicator of high risk for LBP. In that
study, the authors attributed lower than expected injury rates in jobs with high turnover to the
“healthy worker effect.” Based on the overall findings, Waters et al. (1999) concluded that, “although
LBP is a common disorder, the lifting index appears to be a useful indicator for determining the risk of
low back pain caused by manual lifting.”
In a study designed to investigate lifting-related musculoskeletal disorders in the metal processing
industry in China, Xiao et al. (2004) used the revised NIOSH equation to analyze the risk factors for

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