CHARACTERISTIC | GROUP 1, BIOMEDICAL DIAGNOSIS (N = 139) | GROUP 2, BIOMEDICAL DIAGNOSIS AND PSYCHOLOGICAL FACTORS (N = 214) | GROUP 3, PSYCHOLOGICAL FACTORS (N = 88) |
---|---|---|---|
Female to male ratio | 1.3 | 1.1 | 1.2 |
Disability payment source, % (mean [SD] age of patients, y)* | |||
• CPP | 46.0 (68.0 [10.3]) | 13.9 (59.8 [16.4]) | 11.5 (55.7 [14.5]) |
• LTD | 19.2 (49.6 [7.8]) | 15.3 (51.2 [8.2]) | 11.5 (41.2 [14.6]) |
• WSIB | 17.6 (45.7 [8.3]) | 37.2† (46.6 [7.1]) | 40.1† (43.4 [10.9]) |
• ODSP | 6.9 (50.2 [8.7]) | 19.0† (44.0 [11.5]) | 21.2† (40.6 [13.7]) |
Mean (SD) SFMGPQ score‡ | 6.8 (3.9) | 9.0§ (3.6) | 9.2§ (3.8) |
Mean (SD) NRS primary pain rating|| | 5.2 (2.6) | 7.0† (2.2) | 6.5† (2.8) |
Mechanisms of pain, % | |||
• NP | 51.0 | 31.3 | NA¶ |
• MSK | 41.7 | 54.7 | NA¶ |
• NP and MSK | 5.0 | 9.4 | NA¶ |
• Visceral | 2.2 | 3.3 | NA¶ |
Most common etiology (proportion of patients) | Mechanical low back pain (13.7); nerve injury (10.8) | Mechanical low back pain (13.6); nerve injury (8.4); regional myofascial pain (10.3) | NA |
CPP—Canada Pension Plan, LTD—long-term disability, MSK—musculoskeletal, NA—not applicable, NP—neuropathic pain, NRS—numerical rating score, ODSP—Ontario Disability Support Program, SFMGPQ—Short Form of the McGill Pain Questionnaire, WSIB—Workplace Safety and Insurance Board.
↵* Group 1, n = 74; group 2, n = 137; group 3, n = 52.
↵† Statistically significant (P < .001) by Bonferroni correction for the difference between group 1 and groups 2 and 3. No difference was found between groups 2 and 3.
↵‡ Score is the number of words selected from the moderate and severe pain intensity categories of the SFMGPQ; higher scores suggest more severe pain.
↵§ Statistically significant (P < .01) by Bonferroni correction for the difference between group 1 and groups 2 and 3. No difference was found between groups 2 and 3.
↵|| Primary pain was rated on a scale of 0 to 10.
↵¶ Not detectable with available technology (electrophysiological and imaging studies).