Healthcare costs associated with nephrology care in pre-dialysis chronic kidney disease patients

Figures & data

Figure 1.  Study design scheme.

Figure 2.  Patients’ disposition. *Defined as ≥1 CKD claim + ≥1 eGFR <60 mL/min/1.73 m² + ≥2 Hb readings; †Categories not mutually exclusive. CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; Hb, hemoglobin.

Table 1.  Study population characteristics.

Variable	Nephrology care settings (n = 1,547)	Other care settings (n = 18,588)	p-value
Women, n (%)	591 (38.2)	8,077 (43.5)	<0.0001
Age, years, mean (SD)	59.6 (13.2)	61.2 (12.2)	<0.0001
Observation period*, years, mean (SD)	2.8 (1.6)	2.7 (1.5)	0.0680
overall duration of anemia periods per patient	0.9 (0.9)	1.0 (1.0)	0.0060
overall duration of non-anemia periods per patient	2.5 (1.6)	2.6 (1.5)	0.2078
Hb at baseline, g/dL, mean (SD)	12.8 (1.9)	13.1 (1.8)	<0.0001
eGFR at baseline, mL/min per 1.73 m^2, mean (SD)	36.2 (14.4)	43.8 (12.6)	<0.0001
CKD stage at baseline, n (%)
Stage 3	996 (64.4)	15,593 (83.9)
Stage 4	413 (26.7)	2,508 (13.5)	<0.0001
Stage 5	138 (8.9)	487 (2.6)
Comorbidities, n (%)
Hypertension	1,468 (94.9)	17,382 (93.5)	0.0190
Diabetes	799 (51.6)	10,542 (56.7)	0.0001
CAD	685 (44.3)	9,102 (49.0)	0.0004
LVH	334 (21.6)	4,636 (24.9)	0.0022
MI	316 (20.4)	4,373 (23.5)	0.0039

CAD, coronary artery disease; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; Hb, hemoglobin; LVH, left ventricular hypertrophy; MI, myocardial infarction; SD, standard deviation.

*Patients were observed from the date of 1st Hb reading or eGFR <60 mL/min/1.73 m², whichever occurred later, until the end of health-plan enrollment, 30 days prior to a renal dialysis claim, or the study end date of September 2007, whichever occurred earlier.

Table 2.  Unadjusted and adjusted healthcare cost difference between CKD patients cared for in nephrology clinics and other care settings: all patients.

	Univariate analysis (unadjusted)					Multivariate analysis (adjusted)†
Annualized healthcare costs* ($)	Nephrology care settings [A]	Other care settings [B]	Cost ratio [A]/[B]	Cost difference [A] − [B]	p-value	Cost difference	p-value
All patients	(n=1,547)	(n=18,588)
Outpatient services	$5,483	$6,384	0.9	−$901	0.0035	−$926	0.0020
Inpatient services	$4,654	$6,096	0.8	−$1,442	0.0524	−$1,129	0.0539
Pharmacy costs	$1,166	$1,872	0.6	−$706	<0.0001	−$687	0.0060
Total costs	$11,303	$14,352	0.8	−$3,049	0.0014	−$2,742	0.0060

eGFR, estimated glomerular filtration rate; Hb, hemoglobin; CKD, chronic kidney disease.

*Patients were observed from the date of 1st Hb reading or eGFR <60 mL/min/1.73 m², whichever occurred later, until the end of health-plan enrollment, 30 days prior to a renal dialysis claim, or the study end date of September 2007, whichever occurred earlier.

†After controlling for eGFR and Hb at baseline, age, gender, and comorbidities (hypertension, angina, cardiac arrest, cardiac arrhythmia, congestive heart failure, stroke, diabetes, coronary artery disease, acute myocardial infarction, and left ventricular hypertrophy).

Table 3.  Unadjusted and adjusted healthcare cost difference between CKD patients cared for in nephrology clinics and other care settings by CKD stage at baseline.

	Univariate analysis (unadjusted)					Multivariate analysis (adjusted)†
Annualized healthcare costs* ($)	Nephrology care settings [A]	Other care settings [B]	Cost ratio [A]/[B]	Cost difference [A] − [B]	p-value	Cost difference	p-value
Stage 3	(n = 996)	(n = 15,593)
Outpatient services	$5,130	$6,216	0.8	−$1,085	0.0031	−$937	0.0060
Inpatient services	$3,771	$5,862	0.6	−$2,091	0.0176	−$1,573	0.0240
Pharmacy costs	$1,230	$1,923	0.6	−$693	<0.0001	−$749	0.0040
Total costs	$10,132	$14,000	0.7	−$3,869	0.0006	−$3,259	0.0020
Stage 4	(n = 413)	(n = 2,508)
Outpatient services	$5,775	$7,258	0.8	−$1,483	0.0136	−$1,177	0.0180
Inpatient services	$5,501	$7,711	0.7	−$2,210	0.1276	−$1,181	0.3437
Pharmacy costs	$1,110	$1,575	0.7	−$465	0.0005	−$408	0.0060
Total costs	$12,386	$16,545	0.7	−$4,158	0.0250	−$2,766	0.0699
Stage 5	(n = 138)	(n = 487)
Outpatient services	$9,272	$9,893	0.9	−$621	0.6257	−$359	0.8192
Inpatient services	$13,687	$7,536	1.8	$6,152	0.0787	$5,793	0.0639
Pharmacy costs	$486	$1,093	0.4	−$608	0.0006	−$495	0.0280
Total costs	$23,445	$18,522	1.3	$4,923	0.2385	$4,938	0.1898

eGFR, estimated glomerular filtration rate; Hb, hemoglobin; CKD, chronic kidney disease.

*Patients were observed from the date of 1st Hb reading or eGFR <60 mL/min/1.73 m², whichever occurred later, until the end of health-plan enrollment, 30 days prior to a renal dialysis claim, or the study end date of September 2007, whichever occurred earlier.

†After controlling for Hb at baseline, age, gender, and comorbidities (hypertension, angina, cardiac arrest, cardiac arrhythmia, congestive heart failure, stroke, diabetes, coronary artery disease, acute myocardial infarction, and left ventricular hypertrophy).

Table 4.  Unadjusted and Adjusted Healthcare Cost Difference between CKD Patients Cared for in Nephrology Clinics and Other Care Settings by Anemia Status.

	Univariate analysis (unadjusted)					Multivariate analysis (adjusted)†
Annualized healthcare costs* ($)	Nephrology care settings [A]	Other care settings [B]	Cost ratio [A]/[B]	Cost difference [A]−[B]	P value	Cost difference	P-value
Anemia periods	(N = 677)	(N = 5,024)
Outpatient services	$7,206	$8,995	0.8	−$1,789	0.0042	−$1,267	0.0260
Inpatient services	$7,173	$10,595	0.7	−$3,423	0.0312	−$2,260	0.0959
Pharmacy costs	$584	$1,521	0.4	−$937	<0.0001	−$874	0.0040
Total costs	$14,963	$21,112	0.7	−$6,149	0.0022	−$4,401	0.0260
Non-anemia periods	(N = 1,283)	(N = 16,443)
Outpatient services	$5,110	$6,008	0.9	−$898	0.0056	−$864	0.0120
Inpatient services	$4,276	$5,633	0.8	−$1,357	0.0868	−$854	0.1578
Pharmacy costs	$1,283	$1,904	0.7	−$621	<0.0001	−$561	0.0020
Total costs	$10,669	$13,545	0.8	−$2,875	0.0046	−$2,278	0.0060

eGFR, estimated glomerular filtration rate; Hb, hemoglobin; CKD, chronic kidney disease.

*Patients were observed from the date of 1st Hb reading or eGFR <60 mL/min/1.73 m², whichever occurred later, until the end of health plan enrollment, 30 days prior to a renal dialysis claim, or the study end date of September 2007, whichever occurred earlier.

†After controlling for eGFR at baseline, age, gender, and comorbidities (hypertension, angina, cardiac arrest, cardiac arrhythmia, congestive heart failure, stroke, diabetes, coronary artery disease, acute myocardial infarction, and left ventricular hypertrophy).