The economic and humanistic costs of chronic lower back pain in Japan

Figures & data

Figure 1 Respondent disposition in NHWS.

Note: ^aThis is the sample of respondents from whom the matched control group was obtained.
Abbreviations: CLBP, chronic lower back pain; NHWS, National Health and Wellness Survey.

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.

Table 2 Pain characteristics among the CLBP sample

	Diagnosed CLBP (N =392)
	%	N
Lower back pain (lumbar area) – how severe is your pain?
Mild	47.4%	186
Moderate	43.9%	172
Severe	8.7%	34
Severity of pain now (0–10; mean, SD)	4.6	2.2
Severity of pain in past week (0–10; mean, SD)	4.5	2.3
Number of years diagnosed with pain (mean, SD)	9.2	9.7
How frequently do you have problems with pain?
Daily	44.6%	175
4–6 times a week	14.5%	57
2–3 times a week	19.1%	75
Once a week	9.2%	36
2–3 times a month	8.7%	34
Once a month or less often	3.8%	15
Lower back pain (lumbar area) – who diagnosed your pain?
General internist	4.6%	18
Gynecologist	1.3%	5
Orthopedist	82.1%	322
Rheumatologist	1.0%	4
Pain management specialist	0.8%	3
Other	10.2%	40
Currently uses prescription medication to treat pain	39.8%	156
Uses prescription NSAID for pain (either oral or topical)	76.3%	119
Uses opioid for pain (either weak or strong opioid)	14.1%	22
Uses antidepressant for pain	2.6%	4
Uses pregabalin for pain	11.5%	18
Uses other type of prescription medication for pain	19.2%	30
Ever used a prescription medication for pain (among those not currently using a prescription)	62.7%	148
Uses over the counter products for pain	28.1%	110
Uses herbal products for pain	3.1%	12

Abbreviations: CLBP, chronic lower back pain; NSAID, nonsteroidal anti-inflammatory drug.

Figure 2 Health-related quality of life in CLBP patients and matched controls (regression-adjusted [estimated] means with 95% confidence intervals).

Note: ^ap<0.001, indicating results that are statistically significantly higher than results for the same measure in the comparison group.
Abbreviations: CLBP, chronic lower back pain; MCS, mental component summary; PCS, physical component summary; SF-6D, a preference-based, single index measure for health using general population values.

Table 3 Health-related quality of life in CLBP patients and matched controls

Matched comparisons (unadjusted)	Diagnosed CLBP (N=392)		No back pain (N=392)		p-value
	Mean	SD	Mean	SD
MCS	43.6	10.2	48.8	10.8	<0.001
PCS	43.1	14.7	51.0	11.5	<0.001
SF-6D	0.67	0.12	0.77	0.13	<0.001

Abbreviations: CLBP, chronic lower back pain; MCS, mental component summary; PCS, physical component summary; SF-6D, a preference-based, single index measure for health using general population values.

Figure 3 Work and activity impairment in CLBP patients and matched controls (regression-adjusted [estimated] means with 95% confidence intervals).

Note: ^ap<0.001, indicating results that are statistically significantly higher than results for the same measure in the comparison group.
Abbreviation: CLBP, chronic lower back pain.

Table 4 Work and activity impairment in CLBP patients and matched controls

Matched comparisons (unadjusted)	Diagnosed CLBP (N=392)		No back pain (N=392)		p-value
	Mean	SD	Mean	SD
Absenteeism (%)	5.1	18.4	2.8	14.2	0.159
Presenteeism (%)	31.2	27.6	21.5	26.4	<0.001
Overall work impairment (%)	33.8	29.8	22.5	27.9	<0.001
Activity impairment (%)	37.3	29.5	22.2	27.0	<0.001

Abbreviation: CLBP, chronic lower back pain.

Figure 4 Costs (¥ per patient, per year) in CLBP patients and matched controls (regression-adjusted [estimated] means with 95% confidence intervals).

Note: ^ap<0.001, ^bp<0.01, indicating results that are statistically significantly higher than results for the same measure in the comparison group.
Abbreviations: CLBP, chronic lower back pain; ER, emergency room.

Table 5 Healthcare resource use: bivariate comparisons for continuous variables

Matched comparisons (unadjusted)	Diagnosed CLBP (N=392)		No back pain (N=392)		p-value
	Mean	SD	Mean	SD
HCP visits in the prior 6 months	12.90	16.43	4.67	8.29	<0.001
ER visits in prior 6 months	0.31	1.98	0.08	0.53	0.028
Hospitalizations in prior 6 months	1.31	6.44	0.91	6.79	0.400
Regression-estimated (adjusted) means	Mean	SE	Mean	SE	p-value
HCP visits	11.4	0.9	4.8	0.4	<0.001
ER visits	0.16	0.05	0.09	0.03	0.163
Hospitalizations	Regression failed to converge

Abbreviations: CLBP, chronic lower back pain; ER, emergency room; HCP, healthcare provider; SE, standard error.

Table 6 Estimated medical costs according to presence of CLBP (per patient per year)

Matched comparisons	Diagnosed CLBP (N=392)		No back pain (N=392)		p-value
	Mean	SD	Mean	SD
ER direct costs (¥)	19,382	123,035	5,243	32,765	0.028
Physician direct costs (¥)	213,091	271,325	77,070	136,996	<0.001
Hospital direct costs (¥)	1,471,156	7,251,726	1,022,913	7,649,214	0.400
Indirect costs (¥)	1,543,316	1,510,005	1,071,727	1,421,971	0.001
Total direct costs (¥)	1,703,629	7,308,301	1,105,226	7,710,411	0.265

Abbreviations: CLBP, chronic lower back pain; ER, emergency room.

Figure 5 Costs (¥ per patient, per year) in CLBP patients and matched controls (means weighted by age and sex with ±1 standard deviation error bars).

Abbreviations: CLBP, chronic lower back pain; ER, emergency room.