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Table 4 Decomposition of effects of social class on physical function in older age

From: Working conditions mediate the association between social class and physical function in older age in Sweden: a prospective cohort study

  Mediation analysis of working conditions
Mobility limitations Physical impairment
  Total effects Direct effects Indirect effects Mediation %a Total effects Direct effects Indirect effects Mediation %a
Model 2 Physical working conditions (ref: upper white-collar)
 Lower white-collar 0.30 0.37 −0.07 −23.92 0.51* 0.44 0.08 14.63
 Skilled blue-collar 0.55* 0.70** −0.15 − 26.40 0.50 0.36 0.14 28.80
 Unskilled blue-collar 0.42 0.55* − 0.14 −31.89 0.42 0.28 0.14 32.50
Model 3 Psychosocial working conditions
3a Passive (ref: upper white-collar)
  Lower white-collar 0.30 0.30 0.00 −3.05 0.51* 0.42 0.09 17.59
  Skilled blue-collar 0.55* 0.56* −0.01 −2.50 0.49 0.36 0.14 27.61
  Unskilled blue-collar 0.41 0.43 −0.02 −4.32 0.42 0.23 0.19 45.71
3b High-strain (ref: upper white-collar)
  Lower white-collar 0.30 0.26 0.04 14.41 0.51* 0.52* −0.01 −1.64
  Skilled blue-collar 0.56* 0.56* −0.00 −0.11 0.50 0.50 0.00 0.01
  Unskilled blue-collar 0.41 0.39 0.02 5.98 0.42 0.42 −0.00 −0.91
3c Low-strain (ref: upper white-collar)
  Lower white-collar 0.29 0.25 0.04 15.20 0.51* 0.47 0.04 8.50
  Skilled blue-collar 0.55* 0.51* 0.04 6.54 0.50 0.46 0.04 7.19
  Unskilled blue-collar 0.41 0.37 0.10 23.38 0.42 0.32 0.10 23.92
3d Active (ref: upper white-collar)
  Lower white-collar 0.30 0.32 −0.02 −8.13 0.51* 0.52* −0.01 −1.61
  Skilled blue-collar 0.54* 0.57* −0.03 −5.15 0.50 0.51 −0.01 −1.97
  Unskilled blue-collar 0.41 0.53 −0.03 −7.33 0.42 0.43 −0.01 −2.57
Model 4 Physical and psychosocial working conditions (ref: upper white-collar)
 Lower white-collar 0.31 0.28 0.02 7.92 0.52* 0.33 0.18 35.35
 Skilled blue-collar 0.56* 0.60* −0.04 −8.00 0.50 0.25 0.26* 50.91
 Unskilled blue-collar 0.43 0.42 0.01 3.00 0.42 0.11 0.31* 73.69
  1. aMediation % corresponds to conf_pct in khb decomposition output in STATA 14 which stands for confounding percentage net of rescaling p < 0.10, p < 0.05*, p < 0.01**. Effect size expressed as beta coefficients unless otherwise specified. All models were adjusted for age, sex, level of education, mobility, and health problems at baseline (Model 1). Model 2 was additionally adjusted for physical working conditions. Model 3 was adjusted like Model 1 and additionally for psychosocial working conditions. Model 4 was adjusted like Model 1 and additionally for physical and psychosocial working conditions