Table 1.

Demographics: matched bivariate comparisons

	Diagnosed CLBP				p-value
	Diagnosed CLBP (N=392)		No back pain (N=392)
	%	N	%	N
Female	44.90%	176	42.60%	167	0.517
Age (mean, SD)	53.7	14.2	50.8	14.6	0.005
Married/living with partner	67.90%	266	67.30%	264	0.879
Income					0.96
<¥3,000,000	19.60%	77	19.60%	77
¥3,000,000–<¥5,000,000	23.50%	92	23.00%	90
¥5,000,000–<¥9,000,000	30.40%	119	32.10%	126
¥9,000,000 or more	19.10%	75	17.30%	68
Decline to answer	7.40%	29	7.90%	31
4-Year college graduate	48.00%	188	49.20%	193	0.721
Employed	61.50%	241	60.20%	236	0.714
Body mass index categories					0.001
Underweight	12.00%	47	8.20%	32
Normal	66.10%	259	76.50%	300
Overweight/obese	20.70%	81	13.50%	53
Decline to answer	1.30%	5	1.80%	7
Drinks alcohol	73.00%	286	75.00%	294	0.515
Smokes cigarettes	26.80%	105	20.70%	81	0.044
Vigorous exercise in past month	50.30%	197	44.90%	176	0.133
CCI (mean, SD)	0.55	2.59	0.1	0.33	0.001

Notes: Drinks alcohol refers to “any self-reported alcohol use (versus not)”; smokes cigarettes refers to “current cigarette smoking (versus not)”; vigorous exercise in the past month refers to “report of at least one day of exercise in the prior 30 days (versus not)”.

Abbreviations: CCI, Charlson comorbidity index; CLBP, chronic lower back pain.