The quality of spine surgery from the patient's perspective. Part 1: the Core Outcome Measures Index in clinical practice.

The Core Outcome Measures Index (COMI) is a short, multidimensional outcome instrument, with excellent psychometric properties, that has been recommended for use in monitoring the outcome of spinal surgery from the patient's perspective. This study examined the feasibility of implementation of COMI and its performance in clinical practice within a large Spine Centre. Beginning in March 2004, all patients undergoing spine surgery in our Spine Centre (1,000-1,200 patients/year) were asked to complete the COMI before and 3, 12 and 24 months after surgery. The COMI has one question each on back (neck) pain intensity, leg/buttock (arm/shoulder) pain intensity, function, symptom-specific well being, general quality of life, work disability and social disability, scored as a 0-10 index. At follow-up, patients also rated the global effectiveness of surgery, and their satisfaction with their treatment in the hospital, on a five-point Likert scale. After some fine-tuning of the method of administration, completion rates for the pre-op COMI improved from 78% in the first year of operation to 92% in subsequent years (non-response was mainly due to emergencies or language or age issues). Effective completion rates at 3, 12 and 24-month follow-up were 94, 92 and 88%, respectively. The 12-month global outcomes (from N = 3,056 patients) were operation helped a lot, 1,417 (46.4%); helped, 860 (28.1%); helped only little, 454 (14.9%); did not help, 272 (8.9%); made things worse, 53 (1.7%). The mean reductions in COMI score for each of these categories were 5.4 (SD2.5); 3.1 (SD2.2); 1.3 (SD1.7); 0.5 (SD2.2) and -0.7 (SD2.2), respectively, yielding respective standardised response mean values ("effect sizes") for each outcome category of 2.2, 1.4, 0.8, 0.2 and 0.3, respectively. The questionnaire was feasible to implement on a prospective basis in routine practice, and was as responsive as many longer spine outcome questionnaires. The shortness of the COMI and its multidimensional nature make it an attractive option to comprehensively assess all patients within a given Spine Centre and hence avoid selection bias in reporting outcomes.