Pain outcomes at four years
Pain, pain
SECONDARY
Pain severity data as measured by BPI were available for all participants who responded to the longer-term follow-up. The response rate was 62% (226/363). Pain interference data were available for all but two usual care participants and one intervention participant, with a response rate of 61% (223/363).At four years, the adjusted between-group difference in means for the BPI pain severity score was − 0.42 (95% CI (-1.07, 0.23); 
Primary and selected secondary outcomes at baseline, one- and four-year follow-up

Note: The “intervention effect” is intervention minus usual care, adjusted for baseline BPI Severity and Interference, and site. Secondary outcomes are adjusted for their corresponding baseline values.Analysis making the most extreme assumptions about missing data across the two arms gave different results in direction as well as magnitude, though multiple imputation analyses (assuming the data is missing at random) led to attenuations of about 0.2 points from the above estimates of effect on the two co-primary outcomes. The reduced mice model included BPI severity and interference scores at all time points in chain. Site and baseline BPI severity scale, BPI interference scale, OKS, PainDETECT and HADS scores were included in the prediction model. The full mice model includes all primary and secondary outcomes (with the exception of chronic widespread pain) at all follow up points, computed in chain, and site, gender and baseline BPI severity, and interference, OKS, PainDETECT and HADS, baseline chronic widespread pain, and SF12.OKS scores were higher in the intervention group than with usual care at four years but were not significant (mean between-group difference 2.93 [95% CI -0.02 to 5.89]; 