Healthcare resource utilization and economic impact of a ≥2 g/dL decrease in hemoglobin in osteoarthritis patients

Figures & data

Figure 1.  Study design. Hb, hemoglobin.

Figure 2.  Patient selection process. COX-2, cyclooxygenase-2; NSAID, non-steroidal anti-inflammatory drug; OA, osteoarthritis.

Table 1.  Demographic and clinical characteristics of osteoarthritis patients with ≥2 g/dL hemoglobin drop 6 months before the event date.*

Characteristics	≥2 g/dL hemoglobin drop (n = 228)	≤0.5 g/dL hemoglobin drop (n = 1572)	p-value
Female, n (%)	133 (58.3)	998 (63.5)	0.1324
Age (years), mean (SD)	59.8 (9.3)	58.3 (8.0)	0.0258
Comorbidities^a^b
Charlson comorbidity index composite score, mean (SD)	1.4 (1.9)	0.5 (0.9)	<0.0001
Myocardial infarction, n (%)	6 (2.6)	7 (0.4)	0.0003
Congestive heart failure, n (%)	19 (8.3)	11 (0.7)	<0.0001
Ischemic heart disease, n (%)	1 (0.4)	3 (0.2)	0.4578
Angina, n (%)	19 (8.3)	28 (1.8)	<0.0001
Cerebrovascular disease, n (%)	21 (9.2)	34 (2.2)	<0.0001
Peripheral vascular disease, n (%)	13 (5.7)	18 (1.1)	<0.0001
Stroke, n (%)	21 (9.2)	34 (2.2)	<0.0001
Chronic pulmonary disease, n (%)	39 (17.1)	141 (9.0)	0.0001
Rheumatologic disease, n (%)	6 (2.6)	26 (1.7)	0.2965
Peptic ulcer disease, n (%)	9 (3.9)	10 (0.6)	<0.0001
Diabetes, n (%)	75 (32.9)	223 (14.2)	<0.0001
Renal disease, n (%)	11 (4.8)	5 (0.3)	<0.0001
Malignancy, n (%)	24 (10.5)	73 (4.6)	0.0002
Utilizations^a
Emergency department visits, n (%)	67 (29.4)	257 (16.3)	<0.0001
Physician visit, n (%)	225 (98.7)	1498 (95.3)	0.0180
Hospitalization, n (%)	87 (38.2)	61 (3.9)	<0.0001
Outpatient visit, n (%)	227 (99.6)	1513 (96.2)	0.0092
Medications^a
Warfarin, n (%)	16 (7.0)	27 (1.7)	<0.0001
Other anticoagulant or antiplatelet medication, n (%)	36 (15.8)	46 (2.9)	<0.0001
Steroid, n (%)	33 (14.5)	292 (18.6)	0.132
Proton pump inhibitor, n (%)	84 (36.8)	359 (22.8)	<0.0001

*Event date is defined as the first occurrence of a ≥2 g/dL hemoglobin drop in patients with ≥2 g/dL hemoglobin drop and as the first follow-up hemoglobin measurement in patients with ≤0.5 g/dL hemoglobin drop.

^aComorbidity, utilization, and medication prescribed within 6 months before the event date.

^bComorbidities ICD-9-CM codes: myocardial infarction (ICD-9-CM 410–410.9), congestive heart failure (428–428.9), ischemic heart disease (410 and 411, exclude 4111 and 414), angina (4111, 413), cerebrovascular disease (430–438), peripheral vascular disease (443.9, 441–441.9, 785.4, V43.4, 4438, 44389, 4439), stroke (430–438), chronic pulmonary disease (490–496, 500–505, and 506.4), rheumatologic disease (710.0, 710.1, 710.4, 714.0–714.2, 714.81, and 725), peptic ulcer disease (531–534.9), diabetes (250–250.3 and 250.7), renal disease (582–582.9, 583–583.7, 585, 586, and 588–588.9), and malignancy (140–172.9, 174–195.8, and 200–208.9).

Table 2.  Hemoglobin characteristics of osteoarthritis patients with ≥2 g/dL hemoglobin drop.

	≥2 g/dL hemoglobin drop (n = 228)	≤0.5 g/dL hemoglobin drop (n = 1572)	p-value
Baseline hemoglobin value, g/dL, mean (SD)	14.0 (1.5)	14.0 (1.2)	0.6413
Post-baseline hemoglobin value, g/dL, mean (SD)	11.3 (1.7)	14.0 (1.3)	<0.0001
WHO-defined* anemia, n (%)	175 (76.8)	111 (7.1)	<0.0001

*World Health Organization (WHO)-defined anemia is defined as: hemoglobin ≤12 g/dL for women and ≤13 g/dL for men.

Table 3.  Comparison of GI-specific healthcare resource utilization between patients with ≥2 g/dL hemoglobin drop and patients with ≤0.5 g/dL hemoglobin drop 6 months after event date.*

			Unadjusted		Adjusted^a
	≥2 g/dL hemoglobin drop (n = 228), n (%)	≤0.5 g/dL hemoglobin drop (n = 1572), n (%)	OR	95% CI	OR	95% CI
Upper GI endoscopy	37 (16.2)	65 (4.1)	4.5	2.9–6.9	3.5	2.1–6.0
Colonoscopy	36 (15.8)	137 (8.7)	2.0	1.3–2.9	2.0	1.2–3.2
Sigmoidoscopy	1 (0.4)	2 (0.1)	3.5	0.3–38.3	0.4	0.0–45E8
Small bowel endoscopy	1 (0.4)	1 (0.1)	6.9	0.4–111.0	3.1E7	0.0–216E18
Capsule endoscopy	3 (1.3)	1 (0.1)	20.9	2.2–202.2	28.3	1.7–464.2
Any GI endoscopy	50 (21.9)	180 (11.5)	2.2	1.5–3.1	2.0	1.3–3.0

*Event date is defined as the first occurrence of a ≥2 g/dL hemoglobin drop in patients with a ≥2 g/dL hemoglobin drop and as the first follow-up hemoglobin measurement in patients with a ≤0.5 g/dL hemoglobin drop.

^aAdjusted for baseline demographics (age at event, event year, and gender), comorbidities (Charlson comorbidity index, ischemic heart disease, angina, stroke, and peripheral vascular disease), utilizations (emergency department visits, hospitalization, number of office visits, and number of outpatient visits) and medication (warfarin, anticoagulant medication, steroids, and proton pump inhibitors) prescribed during 6 months before event date.

CI, confidence interval; GI, gastrointestinal; OR odds ratio.

Table 4.  Comparison of healthcare resource utilization between patients with ≥2 g/dL hemoglobin drop and patients with ≤0.5 g/dL hemoglobin drop 12 months after event date.*

	Unadjusted			Adjusted^a
	≥2 g/dL hemoglobin drop (n = 228), Mean (SD)	≤0.5 g/dL hemoglobin drop (n = 1572), Mean (SD)	Relative risk^b (95% CI)	≥2 g/dL hemoglobin drop (n = 228), Mean (95% CI)	≤0.5 g/dL hemoglobin drop (n = 1572), Mean (95% CI)	Relative risk^b (95% CI)
Outpatient visit^c	38.4 (30.2)	20.2 (16.1)	1.9 (1.7–2.1)	26.4 (24.1–29.0)	19.0 (18.2–20.0)	1.4 (1.3–1.5)
Physician visit	26.0 (21.5)	15.8 (13.1)	1.6 (1.5–1.8)	18.2 (16.5–20.0)	14.5 (13.9–15.2)	1.3 (1.1–1.4)
Outpatient ED visit	0.9 (2.0)	1.0 (3.6)	0.9 (0.6–1.4)	0.5 (0.4–0.8)	0.6 (0.5–0.7)	0.9 (0.6–1.4)
Outpatient surgical procedure	4.2 (5.6)	2.4 (3.6)	1.7 (1.4–2.1)	2.9 (2.4–3.6)	2.2 (2.0–2.5)	1.3 (1.1–1.6)
Hospitalization^d	0.6 (1.1)	0.2 (0.5)	3.4 (2.6–4.5)	0.4 (0.3–0.5)	0.2 (0.1–0.2)	2.1 (1.5–2.9)
Inpatient ED visit	0.1 (0.4)	0.0 (0.1)	17.7 (7.4–42.5)	0.0 (0.0–2.0E50)	0.0 (0.0–1.5E49)	12.9 (4.2–39.5)
Inpatient surgical procedure	0.1 (0.4)	0.02 (0.1)	5.3 (2.6–10.7)	0.0 (0.0–4.9E7)	0.0 (0.0–1.4E7)	3.4 (1.4–7.8)
Medication	63.2 (42.7)	39.6 (29.7)	1.6 (1.4–1.8)	50.3 (45.6–55.5)	38.6 (36.8–40.4)	1.3 (1.2–1.4)
Laboratory	6.4 (6.7)	2.9 (2.1)	2.2 (2.1–2.4)	5.0 (4.6–5.5)	2.7 (2.6–2.9)	1.8 (1.7–2.0)

*Event date is defined as the first occurrence of a ≥2 g/dL hemoglobin drop in patients with a ≥2 g/dL hemoglobin drop and as the first follow-up hemoglobin measurement in patients with ≤0.5 g/dL hemoglobin drop.

^aNegative binomial generalized linear model with log link function was used for unadjusted and adjusted results; in addition, the adjusted results considered the following baseline factors: demographics (age at event, event year, and gender), comorbidities (Charlson comorbidity index, ischemic heart disease, angina, stroke, and peripheral vascular disease), utilizations (ED visits, hospitalization, number of office visits, and number of outpatient visits), and medication (warfarin, anticoagulant medication, steroids, and proton pump inhibitors) prescribed during 6 months before event date.

^b‘Relative risk’ in both the adjusted and unadjusted models is the ratio of the mean number of events per person over 12 months in one group (patients with ≥2 g/dL hemoglobin) to another group (patient controls, with ≤0.5 g/dL hemoglobin), allowing for rounding error.

^cThe outpatient visits include physician visits, outpatient surgical procedures, outpatient ED visits, and other outpatient services, which include nursing facility, clinic, rehabilitation, etc.

^dHospitalization includes inpatient ED, inpatient surgical procedures and other inpatient services (services in hospital).

CI, confidence interval; ED, emergency department.

Table 5.  Comparison of healthcare charges between patients with ≥2 g/dL hemoglobin drop and patients with ≤0.5 g/dL hemoglobin drop 12 months after event date.*

	Unadjusted			Adjusted^a
	≥2 g/dL hemoglobin drop ($) (n = 228), Mean (SD)	≤0.5 g/dL hemoglobin drop ($) (n = 1572), Mean (SD)	Relative risk^b (95% CI)	≥2 g/dL hemoglobin drop ($) (n = 228), Mean (95% CI)	≤0.5 g/dL hemoglobin drop ($) (n = 1572), Mean (95% CI)	Relative risk^b (95% CI)
Outpatient^c charges	35,177 (51,227)	13,931 (18,993)	2.5 (2.2–2.9)	22,390 (19,194–26,118)	13,448 (12,521–14,442)	1.7 (1.4–2.0)
Physician charges	10,678 (23,996)	4302 (6040)	2.5 (2.2–2.9)	6726 (5855–7728)	3780 (3545–4031)	1.8 (1.5–2.1)
Outpatient ED charges	893 (2771)	466 (1904)	1.9 (1.4–2.7)	725 (485–1084)	382 (318–458)	1.9 (1.2–2.3)
Outpatient surgical procedure	8980 (14,371)	4933 (11,743)	1.8 (1.3–2.5)	7444 (5336–10,385)	4539 (3888–5298)	1.6 (1.2–2.3)
Hospitalization^d charges	27,623 (63,466)	5300 (19,138)	5.2 (3.5–7.9)	18,891 (11,686–30,538)	5251 (4236–6509)	3.6 (2.2–6.0)
Inpatient ED charges	97 (586)	4 (72)	18.2 (14.4–23.1)	13.2 (10.2–17.2)	2.1 (1.9–2.3)	6.3 (4.8–8.4)
Inpatient surgical procedure charges	777 (5010)	104 (1021)	7.4 (5.3–10.5)	44.5 (33.2–59.6)	17.8 (15.5–20.4)	2.5 (1.8–3.4)
Medication charges	7991 (9027)	4155 (5287)	1.9 (1.7–2.2)	5472 (4847–6177)	4093 (3862–4339)	1.3 (1.2–1.5)
Total charges (hospitalization + outpatient + RX)	70,791 (96,547)	23,385 (33,070)	3.0 (2.6–3.5)	47,766 (41,153–55,442)	23,342 (21,777–25,020)	2.1 (1.8–2.4)

*Event date is defined as the first occurrence of a ≥2 g/dL hemoglobin drop in patients with a ≥2 g/dL hemoglobin drop and as the first follow-up hemoglobin measurement in patients with a ≤0.5 g/dL hemoglobin drop.

^aGamma-generalized linear model with log link function was used for unadjusted and adjusted results; in addition, the adjusted results considered the following baseline factors: demographics (age at event, event year, and gender), comorbidities (Charlson comorbidity index, ischemic heart disease, angina, stroke, and peripheral vascular disease), utilizations (ED visits, hospitalization, number of office visits, and number of outpatient visits), and medication (warfarin, anticoagulant medication, steroid, and proton pump inhibitor) prescribed during 6 months before event date.

^b‘Relative risk’ in both the adjusted and unadjusted models is the ratio of the mean number of charges per person over 12 months in one group (patients with ≥2 g/dL hemoglobin) to another group (patient controls, with ≤0.5 g/dL hemoglobin), allowing for rounding error.

^cThe outpatient visits include physician visits, outpatient surgical procedures, outpatient ED visits, and other outpatient services, which include nursing facility, clinic, rehabilitation, etc.

^dHospitalization includes inpatient ED, inpatient surgical procedures, and other inpatient services (services in hospital).

ED, emergency department; RX, prescription.