Table 4.

Associations between age at menopause and prevalence of chronic LBP in cross-sectional analysis, among women at least 40 years old in HUNT2

	Total number of women in category of age at menopause	Number of women with chronic LBP	Crude AR of chronic LBP (%)	RR (95% CI) with adjustment for age only	RR (95 % CI) with additional adjustment*
Number of women included			11 332	11 332	10 054
Age at menopause (year)
≤40	263	90	34.2	1.10 (0.92 to 1.32)	1.08 (0.88 to 1.32)
41–43	269	88	32.7	1.06 (0.88 to 1.28)	1.05 (0.86 to 1.27)
44–46	743	260	35.0	1.12 (0.98 to 1.27)	1.06 (0.92 to 1.21)
47–49	1170	394	33.7	1.07 (0.96 to 1.20)	1.05 (0.93 to 1.18)
50–52	1859	601	32.3	1.01 (0.90 to 1.13)	1.03 (0.92 to 1.15)
53–55	818	290	35.5	1.09 (0.95 to 1.25)	1.06 (0.91 to 1.23)
≥56	182	46	25.3	0.78 (0.59 to 1.02)	0.79 (0.59 to 1.06)
Premenopausal	6028	1670	27.7	1.00 (reference)	1.00 (reference)
P for categorical effect				0.09	0.56
P for linear trend†				0.15	0.49

*Adjustment for age, BMI, physical activity, education, smoking, nulliparity, age at first delivery and age at menarche.

†Among postmenopausal women.

AR, absolute risk; BMI, body mass index; HUNT, Trøndelag Health Study; LBP, low back pain; RR, relative risk.