A comparison of healthcare utilization and outcomes following skin vs. serum-specific IgE allergy testing

Figures & data

Table 1. Summary statistics by allergy testing type.

	All (n = 168,682)	Skin only (n = 95,179)	sIgE only (n = 57,291)	Skin & sIgE (n = 16,212)
				sIgE before skin (n = 5,946)	Skin before sIgE (n = 5,345)	Concurrent (n = 4,921)
Age group
0–4	13,659 (8.1)	4,920 (8.6)	6,956 (7.3)	707 (11.9)	619 (11.6)	457 (9.3)
5–11	25,528 (15.1)	8,353 (14.6)	14,335 (15.1)	1,016 (17.1)	917 (17.2)	907 (18.4)
12–18	21,191 (12.6)	7,467 (13.0)	11,450 (12.0)	799 (13.4)	749 (14.0)	726 (14.8)
19–64	106,350 (63.0)	36,007 (62.9)	61,104 (64.2)	3,386 (57.0)	3,036 (56.8)	2,817 (57.2)
65 +	1954 (1.2)	544 (1.0)	1334 (1.4)	38 (0.6)	24 (0.5)	14 (0.3)
Sex
Male	68,016 (40.3)	39,167 (41.2)	22,437 (39.2)	2,431 (41.0)	2,068 (38.7)	1,913 (38.9)
Female	100,666 (59.7)	56,012 (58.9)	34,854 (60.8)	3,515 (59.1)	3,277 (61.3)	3,008 (61.1)
Insurance Type
HMO	26,510 (15.7)	13,749 (14.5)	10,140 (17.7)	1,011 (17.0)	763 (14.3)	847 (17.2)
PPO	74,470 (44.2)	43,459 (45.7)	24,067 (42.0)	2,496 (42.0)	2,282 (42.7)	2,166 (44.0)
Other	63,462 (37.6)	35,697 (37.5)	21,503 (37.5)	2,275 (38.3)	2,171 (40.6)	1,816 (36.9)
Missing	4,240 (2.5)	2,274 (2.4)	1,581 (2.8)	164 (2.8)	129 (2.4)	92 (1.9)
Place of Service^a
Office	115,162 (66.4)	93,040 (97.4)	10,960 (19.1)	1,266 (20.4)	5,256 (96.0)	4,640 (52.6)
Outpatient hospital	15,296 (8.8)	2,300 (2.4)	10,427 (18.1)	1,097 (17.7)	123 (2.2)	1,349 (15.3)
Laboratory	42,663 (24.6)	11 (0.0)	35,949 (62.5)	3,808 (61.5)	88 (1.6)	2,807 (31.8)
Other	394 (0.2)	151 (0.2)	189 (0.3)	24 (0.4)	6 (0.1)	24 (0.3)
Provider Specialty^a
PCP	10,920 (6.2)	8,144 (8.4)	1,864 (3.2)	169 (2.7)	345 (6.3)	398 (4.3)
Allergy & Immunology	65,981 (37.6)	58,603 (60.8)	488 (0.8)	221 (3.5)	3,640 (66.0)	3,029 (33.1)
Other	98,698 (56.2)	29,717 (30.8)	55,837 (96.0)	5,888 (93.8)	1,527 (27.7)	5,729 (62.6)

Data are presented as n(%) or mean ± SD.

^a Place of service and provider specialty were tallied at the claims level due to a small percentage of patients having multiple allergy tests on the index date.

HMO: health maintenance organization; PCP: primary care physician; PPO: preferred provider organization.

Table 2. Unadjusted health utilization and outcomes at baseline and 1-year post index testing, by allergy testing patterns.

	Skin only (n = 95179)		sIgE only (n = 57291)		sIgE & skin (n = 16212)
	Mean	SD	Mean	SD	Mean	SD	P-value
BASELINE
PCP visits	2.50	3.86	2.37	4.06	2.30	3.84	<0.001
Allergist & Immunologist Visits	0.71	3.52	0.31	2.15	0.47	2.83	<0.001
Pulmonologist Visits	0.11	0.78	0.15	0.81	0.12	0.67	<0.001
# oral corticosteroid Rx	0.56	1.11	0.51	1.20	0.59	1.20	0.007
# asthma reliever Rx	0.44	1.19	0.44	1.31	0.48	1.25	0.644
# asthma controller Rx	0.33	1.24	0.33	1.33	0.37	1.33	0.502
# biologic Rx	0.01	0.27	0.01	0.34	0.01	0.23	0.005
UC visits	0.25	0.84	0.22	0.73	0.25	0.77	<0.001
ED visits	0.33	0.87	0.38	1.03	0.41	0.91	<0.001
1-YEAR
PCP visits	2.78*	5.35	2.62*	4.35	2.69*	5.00	<0.001
Allergist & Immunologist Visits	4.17*	10.41	0.63*	3.08	3.43*	8.41	<0.001
Pulmonologist Visits	0.15*	1.06	0.26*	1.13	0.20*	1.02	<0.001
# oral corticosteroid Rx	0.46*	1.03	0.46*	1.17	0.55*	1.23	0.554
# asthma reliever Rx	0.43	1.18	0.43	1.32	0.49	1.27	0.355
# asthma controller Rx	0.54*	1.72	0.47*	1.66	0.59*	1.80	<0.001
# biologic Rx	0.03*	0.54	0.06*	0.72	0.07*	0.72	<0.001
UC visits	0.21*	0.74	0.20*	0.68	0.22*	0.77	<0.001
ED visits	0.27*	0.85	0.31*	0.91	0.34*	0.97	<0.001

The baseline period included 0-12 months prior to index allergy testing. The 1-year period included 0–12 months after index allergy testing. P-values listed were based on independent-samples t-test between patients with skin only testing and patients with sIgE only testing.

* indicates statistically significant changes between measures at baseline and 1-year follow up within each patient subgroup, all p < 0.01.

UC: urgent care; ER: emergency department; PCP: primary care provider; Rx: prescription.

Figure 1. Health care utilization and outcomes 0-12 months post index allergy testing, per patient by testing pattern. (a) Prescriptions, (b) Visits.

Table 3. Multivariable linear regression results on the associations between allergy testing patterns and subsequent health utilization and outcomes.

	1-year outcomes (0-12 months post index testing)
	Skin only	sIgE only		Skin & sIgE
		Beta	P-value	Beta	P-value
PCP visits	0 (ref)	−0.06	0.007	0.14	<.001
Allergist & Immunologist Visits	0 (ref)	−3.20	<.001	−0.48	<.001
Pulmonologist Visits	0 (ref)	0.09	<.001	0.05	<.001
# oral corticosteroid Rx	0 (ref)	0.02	<.001	0.09	<.001
# asthma reliever Rx	0 (ref)	−0.01	0.077	0.03	<.001
# asthma controller Rx	0 (ref)	−0.07	<.001	0.02	0.172
# biologic Rx	0 (ref)	0.03	<.001	0.04	<.001
UC visits	0 (ref)	−0.01	0.012	0.0	0.566
ED visits	0 (ref)	0.02	<.001	0.04	<.001

Multivariable linear regression models on 9 health care utilization and outcomes at 1 year (0-12 months) post index testing, adjusted for age, sex, and each health utilization and outcome measure in the previous year (baseline), respectively.

UC: urgent care; ED: emergency department; PCP: primary care provider; Rx: prescription.

Figure 2. Average cost of allergy testing per patient by testing pattern.