The added burden of depression in patients with osteoarthritis in Japan

Figures & data

Table 1 Respondent characteristics for patients with OA with and without depression

	Total (N=565)		No or mild depression (N=502)		Moderate or severe depression (N=63)
	%/Mean	n/SD	%/Mean	n/SD	%/Mean	n/SD	p-value
Age, mean (SD) years	59.1 (12.1)		60.6 (11.0)		47.0 (13.7)		<0.001
<40 years	8.8%	50	6.4%	32	28.6%	18	<0.001
40–49 years	8.3%	47	6.0%	30	27.0%	17
50–59 years	24.6%	139	24.7%	124	23.8%	15
60–69 years	45.1%	255	48.4%	243	19.0%	12
70+ years	13.1%	74	14.5%	73	1.6%	1
Female	58.6%	331	58.6%	294	58.7%	37	0.980
Married or living with partner	73.3%	414	74.9%	376	60.3%	38	0.014
Employed full or part-time	45.3%	256	43.2%	217	61.9%	39	0.005
Annual household income							0.300
<¥3 million	18.4%	104	17.5%	88	25.4%	16
¥3 million to <¥5 million	27.6%	156	27.5%	138	28.6%	18
¥5 million to <¥9 million	29.7%	168	31.1%	156	19.0%	12
¥9 million or more	13.8%	78	13.5%	68	15.9%	10
Decline to answer	10.4%	59	10.4%	52	11.1%	7
Completed 4-year university degree	43.5%	246	42.6%	214	50.8%	32	0.218
CCI							0.053
0	69.9%	395	70.5%	354	65.1%	41
1	20.9%	118	21.3%	107	17.5%	11
2+	9.2%	52	8.2%	41	17.4%	11
BMI categories in kg/m^2							0.157
Underweight (<18.5)	7.6%	43	7.2%	36	11.1%	7
Normal (18.5–24.9)	63.4%	358	65.1%	327	49.2%	31
Overweight (25–29.9)	21.8%	123	20.7%	104	30.2%	19
Obese (≥30)	4.4%	25	4.4%	22	4.8%	3
Decline to answer	2.8%	16	2.6%	13	4.8%	3
Smoking status							0.012
Current smoker	17.3%	98	15.7%	79	30.2%	19
Former smoker	31.3%	177	32.5%	163	22.2%	14
Never smoker	51.3%	290	51.8%	260	47.6%	30
Drinks alcohol	67.4%	381	66.1%	332	77.8%	49	0.063
Vigorous exercise in past month	49.7%	281	50.4%	253	44.4%	28	0.373
Length of arthritis diagnosis, mean (SD) years	9.5 (11.8)		9.7 (12.1)		7.6 (8.9)		0.221
Number of joints affected, mean (SD)	1.8 (1.6)		1.8 (1.5)		2.0 (2.1)		0.239
Severity of arthritis (self-reported)							0.514
Mild	50.1%	283	50.4%	253	47.6%	30
Moderate	38.4%	217	38.6%	194	36.5%	23
Severe	11.5%	65	11.0%	55	15.9%	10
Frequency of problems with arthritis							0.406
Daily	36.3%	205	36.3%	182	36.5%	23
4–6 times a week	8.1%	46	8.2%	41	7.9%	5
2–3 times a week	12.2%	69	11.6%	58	17.5%	11
Once a week	4.4%	25	4.0%	20	7.9%	5
2–3 times a month	11.0%	62	11.2%	56	9.5%	6
Once a month or less often	28.0%	158	28.9%	145	20.6%	13
Use a prescription for OA	30.8%	174	29.7%	149	39.7%	25	0.105

Abbreviations: BMI, body mass index; CC, Charlson Comorbidity Index; OA, osteoarthritis; SD, standard deviation.

Table 2 Health-related quality of life for patients with OA with and without depression^a

	Total (N=565)		No or mild depression (N=502)		Moderate or severe depression (N=63)
	Mean	(SD)	Mean	(SD)	Mean	(SD)	p-value
MCS	47.6	(10.7)	49.7	(8.7)	30.7	(10.6)	<0.001
PCS	46.9	(7.8)	47.4	(7.4)	42.6	(9.7)	<0.001
SF-6D	0.69	(0.12)	0.71	(0.11)	0.54	(0.11)	<0.001
Physical functioning	42.8	(15.9)	43.9	(14.4)	33.3	(22.6)	<0.001
Physical role limitations	43.3	(13.7)	44.9	(12.4)	30.4	(16.7)	<0.001
Bodily pain	42.9	(10.2)	43.9	(9.5)	34.9	(11.7)	<0.001
General health	42.4	(10.8)	43.8	(9.9)	30.9	(10.7)	<0.001
Vitality	45.3	(11.0)	47.1	(9.8)	31.1	(10.4)	<0.001
Social functioning	45.6	(12.9)	47.6	(11.2)	29.4	(14.7)	<0.001
Emotional role limitations	46.0	(12.6)	47.7	(10.9)	31.7	(15.6)	<0.001
Mental health	47.8	(11.1)	50.0	(9.0)	30.3	(10.9)	<0.001

Notes: ^aData are from the self-reported patient survey responses to the Medical Outcomes Study 36-Item Short Form Health Survey version 2 (SF-36v2).  Component scores, MCS and PCS, as well as domain scores range from 0-100, with a mean=50 and standard deviation=10, with higher scores indicating better quality of life. The SF-6D is a health utility score ranging from 0.0 (worst health state) to 1.0 (best health state).

Abbreviations: MCS, Mental Component Summary; PCS, Physical Component Summary; SD, standard deviation; SF-6D, Short-Form 6-Dimensions.

Table 3 Work productivity and activity impairment and health care resource use for patients with OA with and without depression

	Total (N=565)		No or mild depression (N=502)		Moderate or severe depression (N=63)
	Mean	SD	Mean	SD	Mean	SD	p-value
Work productivity and activity impairment^a
Absenteeism (%)^b	3.8	15.8	3.5	15.4	5.5	17.6	0.472
Presenteeism (%)^c	27.0	26.8	22.9	24.3	51.5	27.9	<0.001
Overall work impairment (%)^b	29.2	29.0	24.8	27.0	53.6	28.3	<0.001
Activity impairment (%)	32.5	28.8	29.6	27.3	56.2	29.3	<0.001
Health care resource utilization^d
Physician visits	11.9	16.4	10.7	13.6	21.3	29.5	<0.001
(median, IQR)			(7)	(3–14)	(12)	(5–23)	0.001 ^e
ER visits	0.6	4.9	0.3	2.1	3.0	13.4	<0.001
(median, IQR)			(0)	(0–0)	(0)	(0–0)	0.182 ^e
Hospitalizations	1.6	7.4	1.3	5.6	4.3	15.7	0.002
(median, IQR)			(0)	(0–0)	(0)	(0–0)	0.082 ^e

Notes: ^aThe work and activity impairment scale is a patient-reported outcomes questionnaire that examines used to examine work and activity-related impairment in the past week due to one's health. Higher percentage scores indicates greater impairment; ^bAmong employed respondents only: total=229; no/mild=194; moderate/severe=35); ^cAmong employed respondents only: total=233; no/mild=199; moderate/severe=34); ^dSelf-reported total number of healthcare visits or hospitalization days for all health-related issues in the past 6 months was examined for all respondents; ^eMann-Whitney U test of difference in median values.

Abbreviations: ER, emergency room; HCP, healthcare provider; IQR, interquartile range; SD, standard deviation.

Table 4 Adjusted means of health outcomes for patients with OA with and without depression

	No or mild depression		Moderate or severe depression
	Mean	(SE)	Mean	(SE)	p-value
HRQoL	(N=502)		(N=63)
MCS	48.94	(0.48)	31.72	(1.20)	<0.001
PCS	46.94	(0.42)	41.93	(1.04)	<0.001
SF-6D	0.71	(0.01)	0.54	(0.02)	<0.001
Physical functioning	43.14	(0.84)	32.10	(2.08)	<0.001
Physical role limitations	44.46	(0.71)	30.08	(1.75)	<0.001
Bodily pain	43.33	(0.53)	35.01	(1.32)	<0.001
General health	42.55	(0.54)	30.12	(1.33)	<0.001
Vitality	46.21	(0.53)	32.08	(1.31)	<0.001
Social functioning	46.76	(0.63)	29.79	(1.56)	<0.001
Emotional role limitations	47.17	(0.63)	31.84	(1.55)	<0.001
Mental health	49.14	(0.49)	31.25	(1.22)	<0.001
Work productivity and activity impairment (%)	(N=194)		(N=35)
Absenteeism	3.71	(1.24)	5.15	(2.79)	0.639
Presenteeism	23.14	(1.90)	50.55	(4.45)	<0.001
Overall work impairment	25.01	(2.14)	52.71	(4.81)	<0.001
	(N=502)		(N=63)
Activity impairment	30.65	(1.49)	56.98	(3.70)	<0.001
Healthcare resource utilization	(N=502)		(N=63)
Physician visits	11.79	(0.68)	21.69	(3.10)	<0.001
ER visits	0.31	(0.03)	3.12	(0.52)	<0.001
Hospitalizations	1.39	(0.10)	5.15	(0.88)	<0.001

Notes: ^aGeneralized linear regression models were used for measures with normal distributions (HRQoL and work productivity outcomes) and negative binomial models were run for non-negative count data (healthcare resource utilization). All models were adjusted for age, marital status, employment status, and smoking status that were significant predictors of depression severity at p<0.05 in the bivariate comparisons. Adjusted mean values and standard errors for each outcome are presented at the mean the group variable (none/mild or moderate/severe depression) controlling for each of the covariates. Differences between group mean values (i.e., differences in the indicator variable in the regression model) are indicated using the p-value.

Abbreviations: ER, emergency room; HRQoL, health-related quality of life; MCS, Mental Component Summary; PCS, Physical Component Summary; SE, standard error; SF-6D, Short-Form 6-Dimensions.