Clinical comorbidities, treatment patterns, and direct medical costs of patients with osteoarthritis in usual care: a retrospective claims database analysis

Figures & data

Table 1.  Diagnostic codes used to identify relevant comorbidities.

Comorbidities	ICD-9-CM codes
Cardiovascular disorders
Myocardial infarction	410.X, 412.X
Congestive heart failure	398.91, 402.01, 402.11, 402.91, 404.01, 404.03, 404.11, 404.13, 404.91, 404.93, 425.4–425.9, 428.X
Peripheral vascular disease	093.0, 437.3, 440.X, 441.X, 443.1–443.9, 447.1, 557.1, 557.9, V43.4
Cerebrovascular disease	362.34, 430.X–438.X
Coronary heart disease	410.XX-414.XX
Hypertension	401.X
Hyperlipidemia	272.0, 272.1, 272.2, 272.4
Neuropsychiatric disorders
Depression	296.2X, 296.3X, 300.4, 311
Bipolar disorder	296.4X, 296.5X, 296.6X, 296.7
Anxiety	300.00, 300.5, 300.09, 300.20, 300.22, 300.23, 300.29, 300.3, 308.3
Generalized anxiety disorder	300.02
Panic disorder	300.01, 300.21
Post-traumatic stress disorder	309.81
Psychosis	296.9X, 298.X
Sleep disorders
Insomnia/sleep disorders	780.5X, 307.4X, 347.0X, 347.1X, V69.4
Sleep apnea	780.51, 780.53, 780.57
Diseases of the digestive system
Irritable bowel syndrome	564.1
Gastroesophageal reflux disease	530.11, 530.81
Gastritis	535.00 – 535.5X
Duodenitis	535.6X
Other	520.5–530.10, 530.19–530.7, 530.82–530.9, 536.0–537.X, 540.0–543.X, 550.00–553.XX, 555.0–558.X, 560.XX, 562.00–562.01, 562.10–562.11, 564.2–569.2, 569.41–569.81, 569.84–577.9, 579.X
Musculoskeletal pain conditions
Lupus	710
Diffuse diseases of connective tissue	710.1, 710.2, 710.3, 710.4, 710.5, 710.8, 710.9
Arthritis and other arthropathies	711.XX, 712.XX, 713.X, 714.4X, 714.8X, 714.9X, 716.XX, 717.XX, 718.XX, 719.XX
Rheumatoid arthritis	714.0, 714.1, 714.2
Low back pain	720.0, 720.1, 720.2, 721.3, 722.10, 722.32, 722.5, 722.83, 722.93, 724.00, 724.02, 724.2, 724.5, 724.6, 724.70, 724.71, 724.79, 738.4, 739.3, 739.4, 756.11, 756.12, 805.4, 805.6, 846.0, 846.1, 846.2, 846.3, 846.8, 846.9, 847.2, 847.3, 847.4
Back and neck pain, other than low back pain	720.81, 720.89, 720.9, 721.0, 721.2, 721.5, 721.6, 721.7, 721.8, 721.90, 722.11, 722.30, 722.31, 722.39, 722.4, 722.6, 722.80, 722.81, 722.82, 722.90, 722.91, 722.92, 723.X (except 723.4), 724.01, 724.1, 724.8, 724.9, 737.10, 737.11, 737.12, 737.19, 737.20, 737.21, 737.22, 737.29, 737.30, 756.10, 756.13, 756.14, 756.15, 756.16, 756.17, 756.19, 805.8, 847.9
Rheumatism, excluding the back	725–728.9, 729.3–729.9
Other	730.00–739.X

Table 2.  Prevalence of specific chronic comorbidities in osteoarthritis (OA) patients and controls.

Comorbid diagnosis*	n (%)		Odds ratio (95% CI)	p-value^†
	OA (n = 112,951)	Control (n = 112,951)
Cardiovascular disorders
Myocardial infarction	1,619 (1.4)	970 (0.9)	1.68 (1.68, 1.68)	<0.0001
Congestive heart failure	4,286 (3.8)	1,945 (1.7)	2.25 (2.25, 2.25)	<0.0001
Peripheral vascular disease	5,927 (5.2)	2,602 (2.3)	2.35 (2.35, 2.35)	<0.0001
Cerebrovascular disease	5,588 (4.9)	3,098 (2.7)	1.85 (1.84, 1.85)	<0.0001
Coronary heart disease	11,998 (10.6)	6,489 (5.7)	1.95 (1.95, 1.95)	<0.0001
Hypertension	61,458 (54.4)	35,263 (31.2)	2.63 (2.63, 2.63)	<0.0001
Hyperlipidemia	58,891 (52.1)	37,549 (33.2)	2.19 (2.19, 2.19)	<0.0001
Neuropsychiatric disorders
Depression	14,051 (12.4)	7,267 (6.4)	2.07 (2.06, 2.07)	<0.0001
Bipolar disorder	766 (0.7)	394 (0.3)	1.95 (1.95, 1.96)	<0.0001
Anxiety	7,431 (6.6)	3,939 (3.5)	1.95 (1.95, 1.95)	<0.0001
Generalized anxiety disorder	2,228 (2.0)	1,306 (1.2)	1.72 (1.72, 1.72)	<0.0001
Panic disorder	931 (0.8)	501 (0.4)	1.87 (1.87, 2.00)	<0.0001
Posttraumatic stress disorder	482 (0.4)	310 (0.3)	1.55 (1.55, 1.56)	<0.0001
Psychosis	865 (0.8)	490 (0.4)	1.77 (1.77, 1.77)	<0.0001
Sleep disorders
Insomnia/sleep disorders	13,409 (11.9)	4,735 (4.2)	3.08 (3.08, 3.08)	<0.0001
Sleep apnea	7,381 (6.5)	2,024 (1.8)	3.83 (3.82, 3.84)	<0.0001
Diseases of the digestive system
Irritable bowel syndrome	2,708 (2.4)	980 (0.9)	2.80 (2.80, 2.81)	<0.0001
Gastroesophageal reflux disease	20,432 (18.1)	7,392 (6.5)	3.15 (3.00, 3.16)	<0.0001
Gastritis	6,235 (5.5)	2,271 (2.0)	2.84 (2.84, 2.85)	<0.0001
Duodenitis	491 (0.4)	260 (0.2)	1.89 (1.89, 1.90)	<0.0001
Other	24,734 (21.9)	14,433 (12.8)	1.91 (1.91, 1.91)	<0.0001
Musculoskeletal pain conditions
Lupus	1,121 (1.0)	165 (0.1)	6.85 (6.83, 6.87)	<0.0001
Diffuse diseases of connective tissue	826 (0.7)	115 (0.1)	7.22 (7.20, 7.26)	<0.0001
Arthritis and other arthropathies	69,992 (62.0)	13,858 (12.3)	11.65 (11.64, 11.66)	<0.0001
Rheumatoid arthritis	6,338 (5.6)	721 (0.6)	9.25 (9.24, 9.27)	<0.0001
Low back pain	36,658 (32.5)	13,740 (12.2)	3.47 (3.47, 3.47)	<0.0001
Back and neck pain, other than low back pain	23,020 (20.4)	7,986 (7.1)	3.36 (3.36, 3.37)	<0.0001
Rheumatism, excluding the back	55,667 (49.3)	17,842 (15.8)	5.18 (5.18, 5.18)	<0.0001
Other	32,059 (28.4)	14,878 (13.2)	2.61 (2.61, 2.61)	<0.0001

*Comorbidities defined as ≥1 claim(s) for each comorbidity during the study period.

^†Fisher’s exact tests.

Table 3.  Proportions of osteoarthritis (OA) patients and controls using various pain-related medications.

Medications	n (%)		Odds ratio (95% CI)	p-value*
	OA (n = 112,951)	Control (n = 112,951)
Long-acting opioids	4,677 (4.1)	626 (0.6)	7.75 (7.74, 7.77)	<0.0001
Short-acting opioids	45,588 (40.4)	19,261 (17.1)	3.29 (3.29, 3.29)	<0.0001
Strong opioids	19,527 (17.3)	5,438 (4.8)	4.13 (4.13, 4.14)	<0.0001
Weak opioids	38,128 (33.8)	16,262 (14.4)	3.03 (3.03, 3.03)	<0.0001
Any opioids	45,924 (40.7)	19,342 (17.1)	3.31 (3.31, 3.32)	<0.0001
COX-2 inhibitors^†	9,592 (8.5)	1,383 (1.2)	7.48 (7.48, 7.50)	<0.0001
Non-selective NSAIDs	35,339 (31.3)	11,855 (10.5)	3.88 (3.88, 3.88)	<0.0001
Any NSAIDs	41,925 (37.1)	12,944 (11.5)	4.56 (4.56, 4.56)	<0.0001
Salicylates	770 (0.7)	382 (0.3)	2.02 (2.02, 2.03)	<0.0001
Tramadol	11,105 (9.8)	2,052 (1.8)	5.89 (5.89, 5.90)	<0.0001
Acetaminophen	1,423 (1.3)	846 (0.7)	1.69 (1.69, 1.69)	<0.0001
SSRIs	14,403 (12.8)	11,684 (10.3)	1.26 (1.27, 1.27)	<0.0001
SNRIs	6,044 (5.4)	2,931 (2.6)	2.12 (2.12, 2.12)	<0.0001
Tricyclic antidepressants	3,726 (3.3)	2,041 (1.8)	1.85 (1.85, 1.86)	<0.0001
Tetracyclic and miscellaneous antidepressants	6,553 (5.8)	4,721 (4.2)	1.41 (1.41, 1.41)	<0.0001
Benzodiazepines	15,360 (13.6)	10,276 (9.1)	1.57 (1.57, 1.57)	<0.0001
Sedative and hypnotics	10,825 (9.6)	5,946 (5.3)	1.91 (1.91, 1.91)	<0.0001
Miscellaneous agents	3,190 (2.8)	1,274 (1.1)	2.54 (2.54, 2.55)	<0.0001
Topical agents	3,039 (2.7)	464 (0.4)	6.70 (6.69, 6.72)	<0.0001
Intramuscular botox	12 (0.0)	15 (0.0)	0.8 (0.78, 0.82)	<0.0001

CI, confidence interval; COX, cyclooxygenase; NSAIDs, nonsteroidal anti-inflammatory drugs; SNRIs, serotonin-norepinephrine reuptake inhibitors; SSRIs, selective serotonin reuptake inhibitor.

*Fisher’s exact tests.

^†Includes celecoxib only as other COX-2 inhibitors were not available in the US in 2008.

Table 4.  Number of prescription claims for various pain-related medications among osteoarthritis (OA) patients and controls.

Medications	Number of prescriptions*				p-value^†
	OA (n = 112,951)		Control (n = 112,951)
	Mean (SD)	Median (IQR)	Mean (SD)	Median (IQR)
Long-acting opioids	6.1 (5.9)	3.0 (1.0–11.0)	6.9 (6.0)	5.0 (1.0–12.0)	0.0098
Short-acting opioids	5.1 (5.9)	3.0 (1.0–7.0)	2.7 (3.9)	1.0 (1.0–2.0)	<0.0001
Strong opioids	4.5 (6.4)	2.0 (1.0–5.0)	2.9 (5.0)	1.0 (1.0–2.0)	<0.0001
Weak opioids	4.5 (5.2)	2.0 (1.0–6.0)	2.5 (3.6)	1.0 (1.0–2.0)	<0.0001
Any opioids	5.7 (6.9)	3.0 (1.0–7.0)	2.9 (4.6)	1.0 (1.0–2.0)	<0.0001
COX-2 inhibitors^‡	3.8 (3.3)	3.0 (1.0–5.0)	3.2 (3.2)	2.0 (1.0–4.0)	<0.0001
Non-selective NSAIDs	3.6 (3.2)	2.0 (1.0–5.0)	2.2 (2.2)	1.0 (1.0–2.0)	<0.0001
Any NSAIDs	3.9 (3.3)	3.0 (1.0–5.0)	2.3 (2.4)	1.0 (1.0–3.0)	<0.0001
Salicylates	3.3 (3.8)	2.0 (1.0–4.0)	3.5 (4.1)	2.0 (1.0–4.0)	0.3032
Tramadol	3.5 (3.9)	2.0 (1.0–4.0)	2.8 (3.5)	1.0 (1.0–3.0)	<0.0001
Acetaminophen	3.7 (4.5)	2.0 (1.0–4.0)	3.4 (4.9)	1.0 (1.0–3.0)	0.2865
SSRIs	5.9 (3.9)	5.0 (3.0–9.0)	6.3 (3.9)	6.0 (3.0–10.0)	<0.0001
SNRIs	6.2 (4.3)	5.0 (3.0–10.0)	6.7 (4.6)	6.0 (3.0–11.0)	0.0004
Tricyclic antidepressants	5.0 (4.1)	4.0 (1.0–8.0)	5.3 (4.3)	4.0 (1.0–9.0)	0.0381
Tetracyclic and miscellaneous antidepressants	5.7 (4.5)	4.0 (2.0–9.0)	5.8 (4.5)	4.0 (2.0–9.0)	0.4496
Benzodiazepines	4.9 (4.6)	3.0 (1.0–8.0)	4.4 (4.2)	2.0 (1.0–7.0)	<0.0001
Sedative and hypnotics	5.0 (4.5)	3.0 (1.0–8.0)	4.9 (4.7)	3.0 (1.0–7.0)	0.4038
Miscellaneous agents	2.3 (2.9)	1.0 (1.0–2.0)	2.2 (2.6)	1.0 (1.0–2.0)	0.3455
Topical agents	2.0 (1.8)	1.0 (1.0–2.0)	1.7 (1.5)	1.0 (1.0–2.0)	0.0165
Intramuscular botox	2.3 (1.9)	1.0 (1.0–3.0)	1.8 (0.9)	2.0 (1.0–2.0)	0.4199

COX, cyclooxygenase; IQR, interquartile range; NSAIDs, nonsteroidal anti-inflammatory drugs; SNRIs, serotonin-norepinephrine reuptake inhibitors; SSRIs, selective serotonin reuptake inhibitors.

*Represents magnitude of use among users (individuals with at least one claim) of these medications only.

^†Analysis of covariance models with age and gender as covariates.

^‡Includes celecoxib only as other COX-2 inhibitors were not available in the US in 2008.

Table 5.  Use of healthcare services among osteoarthritis (OA) patients and controls.

Resource use category	OA (n = 112,951)			Control (n = 112,951)			p-value*
	n (%)	Number of visits^†		n (%)	Number of visits^†
		Mean (SD)	Median (IQR)		Mean (SD)	Median (IQR)
Physician office visits
GP/FP	54,690 (48.4)	4.1 (4.0)	3.0 (2.0–5.0)	41,313 (36.6)	2.5 (2.3)	2.0 (1.0–3.0)	<0.0001
Internal medicine	41,408 (36.7)	3.8 (3.8)	3.0 (2.0–5.0)	37,022 (32.8)	2.9 (3.4)	2.0 (1.0–3.0)	<0.0001
Orthopedists	56,392 (49.9)	2.8 (3.2)	2.0 (1.0–3.0)	6,888 (6.1)	2.0 (1.8)	1.0 (1.0–2.0)	<0.0001
Rheumatologist	15,640 (13.8)	3.0 (2.4)	2.0 (1.0–4.0)	1,549 (1.4)	2.7 (3.0)	2.0 (1.0–3.0)	0.0064
Neurologist	9,276 (8.2)	2.3 (2.1)	2.0 (1.0–3.0)	4,528 (4.0)	2.0 (1.5)	1.0 (1.0–2.0)	<0.0001
Anesthesiologists	2,651 (2.3)	3.0 (3.2)	2.0 (1.0–4.0)	373 (0.3)	2.3 (2.8)	1.0 (1.0–2.0)	0.0072
PT/OT/phys med	19,518 (17.3)	11.1 (11.9)	7.0 (2.0–16.0)	4,845 (4.3)	8.2 (9.1)	5.0 (2.0–11.0)	<0.0001
Any physician office visit	112,316 (99.4)	14.3 (13.2)	10.0 (6.0–18.0)	97,722 (86.5)	6.9 (7.9)	4.0 (2.0–8.0)	<0.0001
Emergency room visits	23,828 (21.1)	1.7 (2.0)	1.0 (1.0–2.0)	12,365 (10.9)	1.4 (0.9)	1.0 (1.0–1.0)	<0.0001
Other outpatient visits	111,610 (98.8)	12.7 (12.0)	9.0 (5.0–16.0)	96,976 (85.9)	6.3 (7.9)	4.0 (2.0–8.0)	<0.0001
Total outpatient visits	112,937 (100.0)	21.7 (18.0)	17.0 (9.0–29.0)	102,769 (91.0)	10.1 (11.3)	7.0 (3.0–13.0)	<0.0001
Hospitalizations	18,998 (16.8)	5.5 (8.0)	3.0 (2.0–6.0)	6,102 (5.4)	5.5 (9.1)	3.0 (2.0–6.0)	0.4051

GP/FP, general practice/family practice; IQR, interquartile range; PT/OT/Phys Med, Physical therapy/occupational therapy/physical medicine and rehabilitation.

*Analysis of covariance models with age and gender as covariates.

^†Visits represent unique days of office visits.

Table 6.  Direct medical costs of healthcare services among osteoarthritis (OA) patients and controls in US dollars ($) for the calendar year 2008.

Cost category	Costs ($)				p-value*
	OA (n = 112,951)		Control (n = 112,951)
	Mean (SD)	Median (IQR)	Mean (SD)	Median (IQR)
Medications	2,363.97 (6,041.30)	907.09 (100.20–2,643.30)	1,368.05 (5,078.03)	281.77 (2.5–1329.5)	<0.0001
Physician office visits	1,267.86 (1,493.41)	845.81 (449.90–1,559.90)	584.12 (820.86)	358.03 (136.6–722.6)	<0.0001
Emergency room visits	271.43 (1,109.28)	0 (0)	100.70 (469.02)	0 (0)	<0.0001
Other outpatient visits	4,964.67 (10,168.93)	2,185.17 (715.50–5,578.20)	1,882.37 (5,397.30)	491.26 (111.20–1,730.80)	<0.0001
Total outpatient visits	6,503.96 (10,892.66)	3,580.49 (1,498.70–7,646.00)	2,567.19 (5,831.51)	1,030.63 (345.00–2,685.80)	<0.0001
Hospitalizations	4,037.07 (15,022.74)	0 (0)	1,163.95 (8,751.73)	0 (0)	<0.0001
Total medical cost	12,905.00 (21,883.79)	6,187.58 (2,645.80–14,865.60)	5,099.19 (13,854.69)	1,879.02 (605.60–4,594.70)	<0.0001

*Kruskal–Wallis test.