From these, the weights were computed using the inverse variance method to calculate the heterogeneity statistic Q = 96.23, p < 0.0001, df = 9 ( Egger et al 2001). Because homogeneity was rejected, the DerSimonian and

Laird random effects model was estimated yielding a tau squared equal to 0.19. The corresponding weights and pooled OR of 2.17 (95% CI 1.61 to 2.91) are presented in Figure 2 (see also Figure 3 on the eAddenda for a detailed forest plot.) The 95% CIs of all but one of the studies, as well as that of the pooled result, lie to the right of 1.00, indicating significantly greater risk of absence from usual work among participants whose early expectations about their recovery were poor. For the sensitivity analysis, the standard error of the estimated

ORs of the 5 studies with low risk of bias was computed from the 95% CIs. From these, the weights were computed using the inverse Abiraterone in vivo variance method to calculate the heterogeneity statistic Q = 43.83, p < 0.0001, df = 4 ( Egger et al 2001). Because homogeneity was again rejected, the DerSimonian and Laird random effects model was estimated yielding a tau squared equal to 0.34. The corresponding weights and pooled OR of 2.52 (95% CI 1.47 to 4.31) are presented in Figure 4 (see also Figure 5 on the eAddenda for a detailed forest plot.) The confidence intervals of the five studies with low risk of bias as well as that of our pooled result all lie to the right of 1.00, again indicating significantly greater risk of absence from usual work Gefitinib supplier among participants Rolziracetam whose early expectations about their recovery were poor. In order to detect whether publication bias might be affecting the cohort of studies we included in the review, a regression analysis was performed using precision as a predictor for standard normal deviates (Egger et al 1997). The standard normal deviates were computed by dividing the ORs with their corresponding standard error and the precision was computed as the inverse of the standard error. A marginal t-test of the constant

(t = −0.770) yielded a p value of 0.46 indicating no publication bias, which is in line with the observation that there is no clear asymmetry in the scatterplot ( Figure 6.) This review confirmed that the recovery expectations of patients with acute or subacute non-specific low back pain are a statistically significant predictor of absence from usual work due to progression to chronic low back pain. The odds of remaining absent from work at a given time point beyond 12 weeks after the onset of the pain were two times higher among those with negative expectations about their recovery. This pooled result (OR = 2.17, 95% CI 1.61 to 2.91) indicates a strong predictive value. In addition, our analysis yielded consistent evidence of this prognostic role of patients’ expectations.