摘要：Objectives. We compared the risk of injury for multiple job holders (MJHs) with that for single job holders (SJHs). Methods. We used information from the National Health Interview Survey for the years 1997 through 2011 to estimate the rate of multiple job holding in the United States and compared characteristics and rates of self-reported injury (work and nonwork) for SJHs versus MJHs. Results. Approximately 8.4% of those employed reported working more than 1 job in the week before the interview. The rate of work and nonwork injury episodes per 100 employed workers was higher for MJHs than for SJHs (4.2; 95% confidence interval [CI] = 3.5, 4.8; vs 3.3; 95% CI = 3.1, 3.5 work injuries and 9.9; 95% CI = 8.9, 10.9; vs 7.4; 95% CI = 7.1, 7.6 nonwork injuries per 100 workers, respectively). When calculated per 100 full-time equivalents ( P < .05), the rate ratio remained higher for MJHs. Conclusions. Our findings suggest that working in multiple jobs is associated with an increased risk of an injury, both at work and not at work, and should be considered in injury surveillance. Over the past 5 decades there have been many changes in the nature of work in the United States, primarily driven by shifts in the economy, technological advances, and globalization. 1,2 Nearly half of the civilian employed population in the United States currently have some college education, 3 but a significant number of workers take on part-time work and change jobs several times, especially new graduates in the first few years of employment. 4–6 According to the Bureau of Labor Statistics (BLS) Current Population Survey (CPS), in 2011 approximately 5% of US workers reported working in more than 1 job in the same week. 7 The BLS American Time Use Survey (ATUS), which has a smaller sample and diary format, reports higher rates of multiple job holding in the same week (11% in 2011). 8 Paxson and Sicherman 9 estimated that up to 20% of male US workers are employed in multiple jobs over the course of a year. Employment in multiple jobs can take on many different forms, seldom captured in surveys: seasonal work concurrent or alternating with a primary job, working an additional job on the weekends, 10 working 2 consecutive shifts in separate jobs, possibly full or part time, etc. The discrepancy in the prevalence of multiple job holders (MJHs) from the different national data sources is likely attributable to variations in definitions, or survey or sampling methods. Economists cite 2 main incentives for working in more than 1 job 11–13 : (1) needing extra income, currently constituting approximately 64% of all MJHs 12 and (2) advancing their skills or entrepreneurial opportunity. These different reasons for multiple job holding, however, are likely not mutually exclusive. 14 The effect of working multiple jobs on work and nonwork injury has only been minimally explored. One recent study in Wisconsin reported that youths aged 14 to 18 years who worked in multiple jobs had more injuries and more serious injuries than those who worked in only 1 job. 15 This study, however, was limited to a specific population with a small sample size. None of the current injury surveillance systems in the United States addresses the dynamic fluctuations in type of work, work hours, and work processes during the week or year before an injury. For the past 30 years, occupational injury research and standard surveillance systems have almost exclusively described injury morbidity relative to exposures at the worker’s primary job or the job in which the worker was working when injured. We explored the effect of working multiple jobs on work and nonwork injury by using data from the National Health Interview Survey (NHIS). This strategically weighted sample is designed to produce national estimates representative of the US civilian, noninstitutionalized population on a broad range of health topics. Survey respondents are asked to report whether they worked in more than 1 job in the past week and whether they were injured in the past 3 months. With these data, we estimated the prevalence of MJHs and single job holders (SJHs) in the United States, described similarities and differences in demographic and work characteristics for the 2 groups, and tested our hypothesis that those who work in multiple jobs are at increased risk of both work and nonwork injury compared with those who work in only 1 job. We pooled survey data on multiple job holding and injuries across 15 years (1997–2011). We also compared the prevalence of multiple job holding in the NHIS with published statistics from other national surveys.
