Contingent work and depressive symptoms

1. Contingent work and depressive symptoms Contribution of health selection and moderating effects of employment status Suzanne DeHaney1, Amélie Quesnel-Vallée1,2, Antonio Ciampi1 1 Department of Epidemiology, Biostatistics and Occupational Health 2 Department of Sociology McGill University, Montreal, Quebec, Canada

2. Contingent workers in the U.S. • CPS: “Persons who do not expect their jobs to last or who reported that their jobs are temporary.” • Between 4.0 and 4.9% of total employment (4.1% in 2005) • Lower wages and fringe benefits (Kalleberg et al. 2000; Virtanen et al. 2003) • Higher probability of unemployment and lower wages two and four years in the future (DiPrete et al. 2006)

3. Contingent work and mental health • Meta-analysis found greater mental health morbidity (OR=1.25, 95% CI: 1.14; 1.38). among temporary than permanent workers (Virtanen et al. 2005) • Only one prospective population-based study • Employment instability • Health selection

4. Study • Estimate the effect of contingent work on depressive symptom severity after lag periods of two or four years • Stratify analyses by employment status at outcome measurement • Account for health selection with controls for prior mental health

5. Data • NLSY79 • Contingent work • CPS supplement 1994, 1998, 2000 • Estimate 3: self-employed workers and independent contractors with tenure and expectation of continued employment of one year or less, as well as temporary workers and contract workers, regardless of their current tenure. • Depressive symptoms • CES-D 1992, 1994 (baseline), 1998/2000/2002 (outcome) • Controls • gender (interaction effects non-significant), race, poverty level at T+2, years of education at T-1, marital status at T

6. Analytic strategy • Methods • Generalized linear models for fixed effects using SAS GLM. • Random intercept models were tested • Retrospective power calculations with the %power macro • Nested models • Crude estimates • Model 1: Demographics and baseline CES-D • Model 2: Education • Model 3: Marital status • Model 4: Poverty level

7. Cohort sequential, cross-lagged design

8. Descriptives CPS 2001: 3.0% contingent among 29-39 years old (DiPrete et al. 2006)

9. Crude estimates

10. Model 1: demographics and baseline CES-D

11. Retrospective power calculations (Type I error rate=0.05)

12. Discussion • Crude results in line with recent meta-analysis • Risk exists only among those still employed at outcome measurement • But relationship loses significance and declines in magnitude after adjustment for prior depressive symptoms • Retrospective power calculations raise questions viz. non-employed at T2 results

13. Discussion, cont’d • Importance of mental health selection: Contingent work in mid-30s to 40s in the US • Dimensions of inadequate employment not addressed here include: skill mismatch; status discord; inadequate hours, or involuntary part-time work, or the composition of jobs performed by contingent workers

14. Many thanks: • Canadian Institutes for Health Research, grant MOP 77800 • Fonds de recherche en santé du Québec, grant 5582, career award to Amélie Quesnel-Vallée