Table 5.

Patterns of reporting LBP at 41 and 45 as risks of LBP at 49

LBP	History		LBP at 49 years of age	Probability of LBP at 49 given ‘history’	Probability ratio with the no-no group as reference
	LBP 41	LBP 45	OR [95% CI]	%
‘year’	yes	yes	8.9 [4.3;18.3]	84	2.28
	no	yes	3.3 [1.5;7.6]	66	1.80
	yes	no	2.6 [1.1;6.1]	60	1.63
	no	no	1.0	37	1.00
‘month’	yes	yes	5.9 [3.1;11.2]	64	2.76
	no	yes	2.4 [1.2; 4.7]	42	1.82
	yes	no	2.5 [1.2;5.3]	43	1.85
	no	no	1 .0	23	1.00
‘>30 days/year’	yes	yes	9.5 [4.5;20.2]	58	4.60
	no	yes	5.1 [2.2;11.6]	42	3.35
	yes	no	4.0 [1.5;10.5]	36	2.91
	no	no	1.0	13	1.00
‘seeking care’	yes	yes	17.6 [6.9;45.4]	84	3.70
	no	yes	3.0 [1.5;6.0]	47	2.05
	yes	no	2.0 [0 .9;4.1]	37	1.61
	no	no	1 .0	23	1.00
‘non-trivial’	yes	yes	18.4 [7.2;46.9]	69	6.35
	no	yes	5.0 [2.1;11.8]	38	3.48
	yes	no	3.1 [1.0; 9.6]	28	2.55
	no	no	1.0	11	1.00

Patterns of LBP at the ages of 41 and 45 (columns 2 and 3) as risk factors of LBP at age 49 (column 4). OR = odds ratios with 95% confidence intervals (CI), the probability of being in the subgroup as percentage (%) and the probability ratio with the no-no group