Table 2

Association of neck–shoulder pain (NSP) trajectory class with sick leave (days/month) and work ability (ordinal scale 0–10) over 1 year, referencing low NSP

GEE models
NSick leaveWork ability
P valueRR95% CI
95% CI
P valueOR95% CI
95% CI
Model 1
 Low NSP2921.001.00
 Moderate NSP208<0.0013.281.895.68<0.0012.451.873.21
 Strong NSP178<0.0018.984.7816.89<0.0018.646.3811.69
 Severe NSP70<0.00117.649.3633.23<0.00115.079.9422.85
Model 2
 Low NSP2861.001.00
 Moderate NSP204<0.0013.251.875.64<0.0012.401.833.16
 Strong NSP174<0.0018.614.5416.33<0.0019.036.6212.31
 Severe NSP68<0.00116.008.1731.34<0.00114.779.6322.66
Model 3
 Low NSP2771.001.00
 Moderate NSP199<0.0013.111.755.52<0.0012.431.843.20
 Strong NSP165<0.0017.583.9114.71<0.0018.125.9111.16
 Severe NSP66<0.00113.836.7228.49<0.00112.938.5019.67
  • RR estimates, indicating the relative increase in the number of days on sick leave per month, were obtained using GEE with a Poisson distribution for days on sick-leave (measured at 4-week intervals). ORs indicating the likelihood of a 1-unit reduction in work ability, were obtained using GEE with a multinomial distribution for work ability (measured at 12-week intervals).

  • Model 1: unadjusted.

  • Model 2: adjusted for age, gender and body mass index.

  • Model 3: additionally, adjusted for occupational sector (four categories, referencing administration) and physical work load.

  • GEE, generalised estimation equation; RR, relative risk.