The characteristics of the study population are displayed in . Both groups of working women were more than 98 percent Black, therefore race was not included as a covariate in analyses. By frequency matching design, the average age of participants was nearly identical; 31.3 years among poultry processing workers and 31.4 years in the community comparison group. The poultry workers had been in their jobs for relatively shorter periods of time than the women in the comparison group, although not at a level of statistical significance.
Characteristics of Low Wage Working Women in Northeastern North Carolina.a
While fewer than 23% of study participants were married, over 63% of participants had another adult in the home to help out. Prevalence of another adult in the home to share household responsibilities, number of children in the home, having another chronic health condition, having a second job, and survival time without a paycheck were similar between the poultry processing workers and community comparison workers. Frequency of exhaustion at the end of the working day, working fulltime with over time, and ever having been a smoker were both much more prevalent among the poultry processing workers than among the comparison group.
The comparison group was comprised of women working in a variety of jobs, including retail (22.4%), as nurse's aides (22.4%), fast food (13.4%), and clerical (13.0%). The average hourly wages of the comparison group was $8.30/hour, compared with $8.18 among women employed in poultry processing.
and display the distributions of PHRQoL stratified by worker type. indicates that although community comparison workers had some extremely low scores on the physical function survey, the majority of women scored in the mid to high 50s. In contrast, demonstrates that the poultry workers had a higher proportion of scores in the low to mid 40s. The cut-point of 48.19, represents the lowest quartile of physical function scores among all the study women.
Distribution of physical health related quality of life measures (SF-12) among community comparison group.
Distribution of physical health related quality of life measures (SF-12) among poultry workers.
The prevalence of low PHRQoL in each covariate by category is reported in as well as the crude prevalence ratios comparing category levels. The prevalence of low PHRQoL increased with age. Women 45 and above had 1.71 (95% CI: 1.2, 2.5) times the prevalence of diminished PHRQoL as women 18-24 years of age. Presence of another chronic condition, ever having smoked, and frequency of physical exhaustion at the end of the workday were all associated with an increased prevalence of the outcome.
Prevalence and Crude Prevalence Ratios (95% CI) of Lowest Quartile Physical Health Related Quality of Life Among Working Women in Northeastern North Carolina by Explanatory Covariates
The prevalence of diminished PHRQoL and musculoskeletal symptoms stratified by worker type are presented in . The prevalence of low PHRQoL among poultry processing workers (35.5%) was 2.4 times that among the comparison group (14.7%). Moderate to severe upper-extremity musculoskeletal symptoms were 3.2 times more prevalent in the poultry processing workers (34.4% compared to 10.7%).
Association Between Work in Poultry Processing Versus Other Low-Wage Jobs and the Prevalence of Physical Conditions
In , we provide the prevalence ratios and 95% confidence intervals from the crude log-binomial regression model exploring the association between upper-extremity MS and low PHRQoL. Among both groups, presence of moderate to severe upper-extremity MS symptoms in the past year was associated with low PHRQoL. This effect was stronger (PR 5.25, 95% confidence interval 3.24 - 8.52) in the community comparison group than in poultry workers (PR 2.18, 95% confidence interval 1.61 - 2.94) and subsequent models were stratified by worker status. An analysis of effect measure modification indicated that no other covariates modified the estimated prevalence ratio for the association between MS and low PHRQoL.
Table IV Crude prevalence ratios and 95% confidence intervals for low physical health related quality of life in association with upper-extremity musculoskeletal symptoms according to type of work among 590 low-wage working women in northeastern North Carolina. (more ...)
The adjusted prevalence ratios are displayed in . We elected not to include physical exhaustion in multivariate modeling because it could be affected by the outcome. Smoking status and work hours were not included due to convergence problems. Categorized age and presence of another chronic disease were kept in the model due to a priori considerations and strong associations with both outcome and main exposure; categories of age defined by 10-year intervals were entered as a continuous variable.
Table V Adjusted prevalence ratios and 95% confidence intervals for low physical health related quality of life in association with upper-extremity musculoskeletal symptoms among 590 low-wage working women in northeastern North Carolina.a (Log-binomial model) (more ...)
Adjusting for age in years at baseline and presence of other chronic conditions, upper-extremity MS symptoms were still significantly associated with low PHRQoL in both populations, with a stronger association remaining in the community comparison group (Community PR (95% Confidence Interval (CI)) =4.26 (2.51, 7.24); Poultry PR (95% CI) = 1.89 (1.36, 2.64)). Both prevalence ratios have good precision (Confidence Limit Ratio (CLR) among community comparison=2.8; poultry processing=1.9) and their 95% confidence intervals exclude the null (1.0).
Because of the effect measure modification, the attributable risk and population attributable risk percents of low PHRQoL related to moderate to severe upper extremity MS were estimated for each group of women. The PAR% were similar (28.9% among the poultry workers and 31.3% among the comparison group).
In , the PHRQoL scores among the participants in each worker category are compared with the national averages by age and gender-specific group. The scores of the comparison workers were close to or above the national average for all age groups, while the younger poultry processing workers (less than 40 years of age) had lower PHRQoL than the US national average for women.
Comparison of national averages to study participants PHRQoL scores.a