Table 2. Between Group Analyses.
Differences between groups are noted when patients were categorized by the 2011 American College of Rheumatology survey criteria for fibromyalgia (FM). Except for age, employment status, and compensation for pain,,demographic variables were well balanced between the two groups. Patients categorized as fibromyalgia positive (FM+) using the ACR survey criteria showed profound phenotypic differences for pain intensity, pain interference, neuropathic pain, physical function, depression, anxiety, and duration of pain.
|
FM− (n = 257) |
FM+ (n = 186) |
P value | |
|---|---|---|---|
| Fibromyalgia Score | 8.46 (2.79) | 17.2 (3.89) | < 0.0001 |
| Demographics | |||
| Age (years) | 51.9 (17.5) | 46.9 (13.6) | 0.001 |
| Gender (% Female) | 54.1 | 59.1 | 0.29 |
| Race (% Caucasian) | 89.2 | 85.2 | 0.22 |
| Education (% with college education) | 46.0 | 45.3 | 0.89 |
| Marital Status (% married) | 59.6 | 53.8 | 0.23 |
| Employment Status (% employed) | 41.2 | 25.4 | 0.0005 |
| Compensation for Pain (% Yes) | 18.1 | 33.1 | 0.0005 |
| Type of Compensation (% patients) | |||
| Social Security | 51.2 | 56.4 | 0.20 |
| Long-term Disability | 7.3 | 10.9 | |
| Workers’ Compensation | 14.6 | 9.1 | |
| Sick Leave | 12.2 | 1.8 | |
| No Fault Insurance | 14.6 | 21.8 | |
| Pain Phenotype | |||
| Pain Intensity (BPI) | 6.02 (1.83) | 7.2 (1.54) | < 0.0001 |
| Pain Interference (BPI) | 6.33 (2.11) | 7.95 (1.69) | < 0.0001 |
|
Neuropathic pain descriptors
(PainDETECT) |
14 (7.85) | 22.1 (7.79) | < 0.0001 |
| Physical function (ODI) | 40.3 (16.6) | 55.3 (15.8) | < 0.0001 |
| Physical function (PROMIS) | 31.9 (7.42) | 26.9 (7.81) | < 0.0001 |
| Anxiety (HADS) | 6.61 (3.67) | 11.7 (4.65) | < 0.0001 |
| Depression (HADS) | 7.15 (4.23) | 11.5 (4.4) | < 0.0001 |
|
Duration of Pain (%
patients/category) |
|||
| < 3 months | 8.1 | 1.0 | 0.0096 |
| 3-6 months | 11.4 | 3.1 | |
| 7-12 months | 12.2 | 12.5 | |
| 1-5 years | 35.0 | 42.7 | |
| > 5 years | 33.3 | 40.6 | |
Univariate analyses of differences by the FM status; t-test used with continuous variables (means), chi-square test with binary (%), and Wilcoxon test with ordinal data. Data presented as mean (standard deviation) or percentages, as appropriate.
BPI = Brief Pain Inventory, Pain intensity = mean score of 4 questions regarding pain intensity current, worst, least, and average over last 7 days (0-10, 0 = no pain, 10 = worst pain imaginable); Pain interference = mean score of the seven interference questions of BPI (0-10, 0 = does not interfere, 10 = totally interferes); HADS = Hospital Anxiety and Depression Scalehigher scores indicate more anxiety (0-21) and depressive symptoms (0-21); ODI = Oswestry Disability Index (0-100)- higher score indicates more disability; PainDETECT ([-1]- 38)- higher scores indicate more neuropathic pain; PROMIS = Patient Reported Outcomes Measurement Information System physical function scale short form (10-50)- lower scores indicate lower physical function.