From: Menopausal hormone therapy, oral contraceptives and risk of chronic low back pain: the HUNT Study
 | Total number of womena | Number of women with chronic LBP (%)a | RR (95% CI) with adjustment for age only | RR (95% CI) with comprehensive adjustmentb |
---|---|---|---|---|
Use of systemic MHT | ||||
 Number of women included |  |  | 6007 | 5330 |
 Never | 4559 | 904 (19.8) | 1.00 (reference) | 1.00 (reference) |
 Former | 385 | 79 (20.5) | 1.06 (0.86–1.31) | 1.03 (0.83–1.29) |
 Current | 1063 | 262 (24.6) | 1.30 (1.14–1.47) | 1.30 (1.14–1.49) |
 P for categorical effect |  |  |  < 0.001 | 0.001 |
Duration of use of systemic MHT (year) | ||||
 Number of women included |  |  | 5564 | 4955 |
 Never used | 4559 | 904 (19.8) | 1.00 (reference) | 1.00 (reference) |
 0-2c | 513 | 106 (20.7) | 1.08 (0.90–1.29) | 1.13 (0.94–1.36) |
 3–5 | 321 | 82 (25.5) | 1.36 (1.11–1.66) | 1.39 (1.12–1.72) |
 6–8 | 96 | 26 (27.1) | 1.48 (1.06–2.08) | 1.45 (1.02–2.07) |
 ≥ 9 | 75 | 26 (34.7) | 1.83 (1.33–2.51) | 1.84 (1.31–2.59) |
 P for categorical effect |  |  |  < 0.001 | 0.001 |
 P for linear trendd |  |  | 0.001 | 0.003 |
Use of systemic MHT by type in current users | ||||
 Number of women included |  |  | 5554 | 4933 |
 Never used systemic | 4559 | 904 (19.8) | 1.00 (reference) | 1.00 (reference) |
 Oestrogen only | 216 | 56 (25.9) | 1.37 (1.08 -1.74) | 1.49 (1.16–1.91) |
 Combination | 779 | 195 (25.0) | 1.33 (1.16–1-54) | 1.35 (1.16–1.57) |
 P for categorical effect |  |  |  < 0.001 |  < 0.001 |
 P for difference between oestrogen only and combination |  |  | 0.54 | 0.18 |