Persistent back pain after spinal anaesthesia in the non-obstetric setting: incidence and predisposing factors

We determined the incidence of persistent back pain (PBP) after non-obstetr ical spinal anaesthesia (SPA) and investigated factors predisposing to such pain in a prospective I yr follow-up study in 245 patients undergoing elec tive general or trauma surgery (218 patients undergoing single SPA, 27 unde rgoing two to six SPAs). All patients received a first questionnaire 3 mont hs after the last SPA, and those reporting PBP after 3 months were sent a s econd questionnaire I year after the operation. Variables were PBP before a nd within 5 days, at 3 months and I year after SPA, patient satisfaction wi th SPA, patient characteristics and technical data. Statistical analysis wa s by contingency tables with Fisher's exact test and an unpaired t-test wit h logistic regression (P<0.001 after Bonferroni correction was taken as sig nificant). The response rate in patients who had a single SPA was 56% (122/ 218). Twenty-three of these 122 patients (18.9%) complained of back pain be fore SPA compared with 12/122 (10.7%, P=0.0015) within 5 days after SPA. Af ter 3 months, 15/122 patients (12.3%) reported PBP with 14 complaining of P BP before SPA (P<0.0001), corresponding to an incidence of new PBP of 1/122 (0.8%). Multiple logistic regression revealed that pre-existing back pain was the only variable associated with PBP after 3 months (P<0.0001). Patien t characteristics and technical factors were not associated with PBP. Nine of the 15 patients with PBP after 3 months returned the second questionnair e: four still reported PBP (three of these had suffered from PBP before SPA ). Despite PBP after 3 months, 13/15 patients said they would opt for SPA a gain. The response rate and results in patients who had had multiple SPAs w ere similiar to those who had had a single SPA.