Impact of the number of pain sites on work ability
As shown in Table 2, the prevalence of poor work ability
in participants who had no pain, few pain sites, and
many pain sites were 18.4 %, 30.4 %, and 41.0 %, respectively.
In crude analysis, a statistically significant association
was found between the number of pain sites and
work ability. Odds ratio of poor work ability in participants
who had few pain sites was 1.9 (95 % CI 1.01 –
3.69), while in those who had many pain sites was 3.0
(95 % CI 1.42 – 6.68).
To eliminate the effect of confounders, logistic regression
analysis was conducted. All of the potential
confounders were tested for multicollinearity diagnostics.
A formal-detection tolerance of all of these
ranged from 0.6 to 0.9, so there was no multicollinearity
problem. After adjustment for many confounders,
odds ratio in those who had few pain sites
showed no statistical significance (1.89 (95 % CI 0.93
– 3.80)), whereas those who had many pain sites still
showed statistical significance although its odds ratio
showed a small decrease (2.44 (95 % CI 1.06 – 5.66)).