Which factors can aid clinicians to identify a risk of pain during the following month in patients with bone metastases? A longitudinal analyses

PURPOSE: Explore clinical factors associated with higher pain intensity and future pain in patients with bone metastases to identify patients who can benefit from closer follow-up or pain-modifying interventions.

METHODS: This is a secondary analysis of 606 patients with bone metastases included in a multicenter longitudinal study. The dependent variables were "average pain" and "worst pain" in the last 24 h (0-10 NRS). Twenty independent variables with potential association to pain intensity were selected based on previous literature. Cross-sectional analyses were performed with multiple linear regression to explore factors associated with pain intensity at baseline. Longitudinal data were analyzed with a generalized equation models to explore current factors associated with pain intensity at the next visit in 1 month.

RESULTS: Current pain intensity (p < 0.001), sleep disturbances (p 0.01 and 0.006), drowsiness (p 0.003 and 0.033) and male gender (p 0.045 and 0.001) were associated with higher average and worst pain intensity in 1 month. In addition, breakthrough pain was related to higher worst pain intensity (p 0.003) in 1 month. The same variables were also associated with higher average pain intensity at baseline.

CONCLUSION: Higher current pain intensity, sleep disturbances, drowsiness, male gender, and breakthrough pain are factors associated with higher pain intensity in patients with bone metastases at the next follow-up in 1 month. These factors should be assessed in clinical practice and may aid clinicians in identifying patients that can benefit from closer follow-up or interventions to prevent lack of future pain control. TRIAL REGISTRATION IN CLINICALTRIALS.GOV : NCT01362816.