The impact of ribavirin on real-world adherence rates in hepatitis C patients treated with sofosbuvir plus simeprevir

Figures & data

Table 1 MarketScan^® database: patient attrition

	Patients excluded	Patients remaining
Number of patients with at least one sofosbuvir prescription initiated from December 2013 to September 2014	0	5,779
Attrition reason
Number of patients on sofosbuvir and simeprevir from December 2013 to 31 September 2014	4,059	1,720
At least 6 months of pre-index and 12 weeks of post-index eligibility	731	989
Delete patients who did not have HCV diagnosis before index date	47	942
Delete patients who had ≥84 days of supply	32	910
Number of patients in cohort sofosbuvir + simeprevir	0	788
Number of patients in cohort sofosbuvir + simeprevir + ribavirin	0	122

Abbreviation: HCV, hepatitis C virus.

Table 2 Optum database: patient attrition

	Patients excluded	Patients remaining
Number of patients with at least one sofosbuvir prescription initiated from December 2013 to July 8, 2014		1,900
Attrition reason
Number of patients on sofosbuvir and simeprevir from December 2013 to Sep 31, 2014	1,261	639
At least 6 months of pre-index and 12 weeks of post-index eligibility	117	522
Delete patients who did not have HCV diagnosis before index date	3	519
Delete patients who had ≥84 days of supply	0	519
Number of patients in cohort sofosbuvir + simeprevir		440
Number of patients in cohort sofosbuvir + simeprevir + ribavirin		79

Abbreviation: HCV, hepatitis C virus.

Table 3 Baseline characteristics of patients from the MarketScan^® database

Variables	SOF + SIM (n=788)	SOF + SIM + RBV (n=122)	P-value
Age, mean (SD)	56.8 (6.9)	56.7 (6.9)	0.8815
Sex, % male	65.4%	72.1%	0.1506
Co-pay, mean (SD), median	$199.50 (602.2), $80	$337.70 (1,447.8), $107.5	0.0656
Co-pay category
$0–$25 (%)*	21.6%	15.6%	N/A
$26–$50 (%)*	14.1%	4.1%	N/A
$51–$100 (%)*	28.3%	27.9%	N/A
>$100 (%)*	36.0%	52.5%	N/A
Cirrhosis, %	42.8%	56.6%	0.0046
Treatment experienced, %	9.9%	16.4%	0.0403
Charlson Comorbidity Index, mean (SD)	2.71 (2.83)	2.72 (2.91)	0.9711

Notes:

* Overall distributional differences between the cohorts; P<0.05. All currency is in 2014 USD.

Abbreviations: SOF, sofosbuvir; SIM, simeprevir; RBV, ribavirin; SD, standard deviation.

Table 4 Baseline characteristics of patients from the Optum database

Variables	SOF + SIM (n=440)	SOF + SIM + RBV (n=79)	P-value
Age, mean (SD)	57.3 (7.6)	55.1 (7.8)	0.0187
Sex, % male	63.6%	65.8%	0.7993
Co-pay, mean (SD), median	$346 (1,009), $95	$404 (1,306), $110	0.6542
Co-pay category
$0–$25 (%)*	5.2%	3.8%	N/A
$26–$50 (%)*	3.4%	0.0%	N/A
$51–$100 (%)*	55.7%	29.1%	N/A
>$100 (%)*	35.7%	67.1%	N/A
Cirrhosis, %	42.5%	55.7%	0.0363
Treatment experienced, %	12.5%	13.9%	0.7149
Charlson Comorbidity Index, mean (SD)	2.67 (2.96)	2.48 (2.65)	0.5940

Notes:

* Overall distributional differences between the cohorts; P<0.05. All currency is in 2014 USD.

Abbreviations: SOF, sofosbuvir; SIM, simeprevir; RBV, ribavirin; SD, standard deviation.

Table 5 Composite adherence rates for patients treated with SOF + SIM or SOF + SIM + RBV from the MarketScan^® or Optum database

	Unadjusted adherence rates			Adjusted adherence rates
	SOF + SIM	SOF + SIM + RBV	P-value	SOF + SIM	SOF + SIM + RBV	P-value
MarketScan^®
Number of patients in cohort	n=788	n=122	N/A	n=788	n=122	N/A
Adherence rate for SOF	92.6%	90.2%	0.1101	92.2%	89.3%	0.0514
Adherence rate for SIM	92.6%	89.1%	0.0153	92.2%	88.1%	0.0058
Composite adherence rate for SOF and SIM	92.6%	89.7%	0.0423	92.2%	88.7%	0.0176
Optum
Number of patients in cohort	n=440	n=79	N/A	n=440	n=79	N/A
Adherence rate for SOF	94.8%	95.6%	0.5488	94.8%	95.1%	0.8409
Adherence rate for SIM	94.8%	95.6%	0.5755	94.8%	95.1%	0.8772
Composite adherence rate for SOF and SIM	94.8%	95.6%	0.5618	94.8%	95.1%	0.8589

Abbreviations: SOF, sofosbuvir; SIM, simeprevir; RBV, ribavirin; SD, standard deviation.

Table 6 MarketScan^® database: generalized linear model results for calculating composite adjusted adherence rates*

Parameter	Estimate	Standard error	P-value	Interpretation
Intercept	0.8291	0.0452	<0.001	N/A
SOF + SIM + RBV	−0.0333	0.0146	0.0230	SOF + SIM + RBV had 3.3% lower adherence than SOF + SIM
Female sex	0.0002	0.0105	0.9854	Not significant
Age, years	0.0017	0.0007	0.0162	For every 1 year increase in age, adherence increased by 0.17%
Co-pay $0–$25	−0.0320	0.0134	0.0174	Compared to a co-pay >$100, a co-pay of $0–$25 had a 3.1% lower adherence
Co-pay $26–$50	−0.0335	0.0160	0.0364	Compared to a co-pay >$100, a co-pay of $26–$50 had a 3.3% lower adherence
Co-pay $51–$100	−0.0183	0.0122	0.1337	Not significant
Charlson Comorbidity Index	−0.0018	0.0018	0.3160	Not significant
No cirrhosis	−0.0017	0.0101	0.8641	Not significant
Treatment-naïve	0.0236	0.0159	0.1375	Not significant

Notes:

* Similar findings for SIM only and SOF only. All currency is in 2014 USD.

Abbreviations: SOF, sofosbuvir; SIM, simeprevir; RBV, ribavirin; N/A, not applicable.

Table 7 Optum database: generalized linear model results for calculating composite adjusted adherence rates*

Parameter	Estimate	Standard error	P-value	Interpretation
Intercept	0.9643	0.0442	<0.0001	N/A
SOF + SIM + RBV	0.0027	0.0150	0.8589	Not significant
Female sex	−0.0027	0.0110	0.8051	Not significant
Age, years	0.0004	0.0007	0.6063	Not significant
Co-pay $0–$25	−0.0142	0.0251	0.5725	Not significant
Co-pay $26–$50	−0.0543	0.0319	0.0887	Not significant
Co-pay $51–$100	−0.0156	0.0112	0.1633	Not significant
Charlson Comorbidity Index	0.0001	0.0019	0.9542	Not significant
No cirrhosis	0.0014	0.0112	0.9031	Not significant
Treatment-naïve	−0.0295	0.0157	0.0611	Not significant

Notes:

* Similar findings for SIM only and SOF only. All currency is in 2014 USD.

Abbreviations: SOF, sofosbuvir; SIM, simeprevir; RBV, ribavirin; N/A, not applicable.