A systematic review and meta-analysis of three risk factors for chronic postsurgical pain: age, sex and preoperative pain.

Introduction: Chronic postsurgical pain (CPSP) is a common and disabling postoperative complication. Several risk factors for CPSP have been established, but it is unclear whether they are significant for any type of surgery. This systematic review aimed to assess the risk of CPSP related to three known preoperative risk factors "age, sex and preoperative pain" in the adult population after any type of elective non-obstetrical surgery.

Evidence Acquisition: We conducted a systematic literature search using PubMed and EMBASE databases retrieving 1458 abstracts; 320 publications were screened and 71 papers were included. Odds ratios were combined across studies and quality of evidence graded using GRADE. Sub-groups comparisons were conducted for type of surgery, time point for CPSP and definition of CPSP.

Evidence Synthesis: The pooled unadjusted ORs were 1.34 for female sex, 2.43 for preoperative pain at surgical site, 1.75 for preoperative pain elsewhere and 3.95 for preoperative pain at an unspecified site. The pooled unadjusted OR for age was 2.04 in the younger (age midpoint <40 years) compared with the older population of patients (age midpoint >62.5 years). In the subgroup analysis, preoperative pain was a more important risk factor for orthopedic surgery and age for breast surgery.

Conclusions: This systematic review confirms that younger age, female sex, and preoperative pain are associated with higher risk of developing CPSP in any type of elective non-obstetrical surgery. However, effect sizes are small and quality of evidence low-moderate only, limiting comparisons of different types of surgery.