Factors associated with adherence to phosphodiesterase type 5 inhibitors for the treatment of pulmonary arterial hypertension

Figures & data

Figure 1.  Sample selection and rate of adherence.

Table 1.  Baseline demographic characteristics by adherence and use of specialty pharmacy.

	Retail pharmacy			Specialty pharmacy
	Non-adherent	Adherent	p-value	Non-adherent	Adherent	p-value
Number of patients (%)	821 (67.7%)	392 (32.2%)		320 (34.4%)	610 (65.6%)
Age group (%)			0.049			0.819
18–34 years	4.38	3.83		1.88	2.79
35–44 years	6.09	4.85		6.56	6.39
45–64 years	29.11	35.20		36.88	37.38
65–74 years	24.12	27.30		26.88	24.10
75+ years	36.30	28.83		27.81	29.34
Mean age (SD)	65.74 (15.22)	64.70 (14.02)	0.256	63.01 (13.43)	64.62 (14.14)	0.690
Gender			0.647			0.782
Female	66.38	65.05		64.69	63.77
Male	33.62	34.95		35.31	36.23
Region (%)			0.079			0.221
Northeast	20.83	17.60		19.06	23.93
Midwest	23.39	28.32		18.13	20.00
South	40.07	42.09		42.50	37.05
West	15.71	11.99		20.31	19.02
Possession of PDE5I prescription with ≥ 90-day supple (%)	2.44	14.29	< 0.001	50.31	64.10	< 0.001
RxRisk score (%)			0.1903			0.2542
Level 1	24.0	29.9		20.9	25.1
Level 2	24.0	21.9		27.8	26.7
Level 3	25.3	23.2		23.1	25.1
Level 4	26.7	25.0		28.1	23.1

Student’s t-tests were performed for continuous variable and Chi-square tests for categorical variables.

Figure 2.  Adherence rate by index medication and use of specialty pharmacy.

Figure 3.  Rate of high adherence by 30-day co-payment and use of specialty pharmacy. *p < 0.05 in Chi-square test using $0–50 as a reference group.

Figure 4.  Rate of high adherence by prescriber specialty and use of specialty pharmacy. *p < 0.05 in Chi-square test using the primary care physician as a reference group.

Table 2.  Primary and sensitivity analyses to assess factors associated with adherence to PAH treatment by use of specialty pharmacy.

Adherence rate (%)	Main analysis (n = 2143)				Sensitivity analysis (n = 1515)
	Retail pharmacy (n = 1213), 32.3%		Specialty pharmacy (n = 930), 65.6%*		Retail pharmacy (n = 1137), 29.6%		Specialty pharmacy (n = 378), 57.9%*
	Odds ratio	95% CI	Odds ratio	95% CI	Odds ratio	95% CI	Odds ratio	95% CI
Index PDE5Is
Revatio	Reference		Reference		Reference		Reference
Adcirca	2.59	(1.60–4.22)	0.96	(0.70–1.32)	2.48	(1.51–4.07)	1.01	(0.65–1.57)
Age
< 65	Reference		Reference		Reference		Reference
65+	1.03	(0.78–1.36)	1.01	(0.75–1.34)	1.05	(0.79–1.40)	0.99	(0.64–1.55)
Gender
Female	0.94	(0.72–1.23)	0.98	(0.73–1.31)	0.96	(0.72–1.26)	1.19	(0.76–1.86)
Male	Reference		Reference		Reference		Reference
Index provider specialty
Primary care providers	Reference		Reference		Reference		Reference
Pulmonologists	1.70	(1.15–2.50)	1.00	(0.64–1.56)	1.66	(1.12–2.46)	1.12	(0.57–2.19)
Other specialists	0.81	(0.56–1.16)	1.16	(0.73–1.83)	0.79	(0.55–1.15)	1.09	(0.54–2.20)
Unknown	1.14	(0.78–1.65)	1.60	(0.96–2.65)	1.10	(0.75–1.62)	1.73	(0.80–3.74)
Average 30-day co-payment of index prescription
$0–$50	Reference		Reference		Reference		Reference
$51–$250	0.61	(0.42–0.90)	0.86	(0.63–1.19)	0.62	(0.41–0.91)	0.56	(0.34–0.91)
$251 or more	0.57	(0.39–0.83)	0.56	(0.35–0.90)	0.58	(0.40–0.85)	0.50	(0.26–1.00)
Possession of prescription with 90-day or greater supply
Yes	5.81	(3.39–9.95)	1.75	(1.32–2.33)	–	–	–	–
No	Reference		Reference		–	–	–	–
RxRisk score
Level 1	Reference		Reference		Reference		Reference
Level 2	0.79	(0.55–1.14)	0.80	(0.54–1.20)	0.81	(0.55–1.18)	1.10	(0.61–1.97)
Level 3	0.79	(0.55–1.15)	0.88	(0.57–1.34)	0.83	(0.57–1.21)	1.08	(0.58–2.02)
Level 4	0.79	(0.56–1.13)	0.66	(0.44–0.99)	0.82	(0.57–1.17)	0.72	(0.40–1.31)

*p < 0.05 in adherence rate between retail and specialty pharmacy cohorts.