Pulmonary arterial hypertension associated with interferon therapy: a population-based study
© The Author(s). 2017
Received: 11 November 2016
Accepted: 14 December 2016
Published: 17 January 2017
Isolated cases of pulmonary arterial hypertension (PAH) with interferon α or β therapy have been reported, but no population-based estimates of the incidence of the disease after interferon exposure are available. The aim of this study was to determine the incidence of PAH after initiation of interferon therapy, using a large commercial insurance database.
Using National Drug Codes (NDCs) and Healthcare Common Procedure Coding System (HCPCS) codes, we utilized the Clinformatics™ Data Mart (CDM) database to identify subjects between 20 and 65 years old who received α or β interferon therapy between April 2001 and December 2012. Patients were followed from one year prior to the first medication claim for interferon to the first diagnosis of pulmonary hypertension using ICD-9-CM codes 416.0 and 416.8, or disenrollment. In those subjects diagnosed with pulmonary hypertension, a prescription for PAH-specific medications was used as a surrogate endpoint.
We identified 20,113 subjects who received interferon therapy during the study period. The median follow-up was 20 months. Pulmonary hypertension occurred in 71 subjects, and PAH-specific medications were prescribed to 7 of these subjects.
Although our analysis showed that the development of PAH is a rare event with interferon therapy, the risk of developing the disease is several fold higher than that for the general population.
In the last quarter of the 20th century, type I interferons, including α and β, were introduced as treatment for malignancies, chronic viral infections, and chronic neurologic conditions [1, 2]. Type I interferons are a family of glycoproteins with potent antiviral, immunomodulatory, and antitumor properties that are naturally generated in the human body, in response to pathogens and tumor cells. Consequently, interferon α was evaluated for the treatment of chronic hepatitis C with reports of sustained virologic response with prevention of further hepatic fibrosis and progressive organ failure [3–5]. In the management of relapsing multiple sclerosis, interferon β has been reported to decrease relapse rates and reduce disease burden when assessed by brain imaging [6, 7].
Although the benefits of interferon therapy are well documented, this medication has several side effects. It is commonly associated with flu-like illness and less often with neuropsychiatric effects (depression) and myelosuppression (pancytopenia). Occurrence of these side effects leads to dose reduction or delays in subsequent treatment and often resolve with drug discontinuation. Pulmonary arterial hypertension (PAH), a rare but serious side effect of interferon therapy, was first reported in a patient with renal cancer . As the indications for interferon expanded to include chronic hepatitis and multiple sclerosis, the frequency of reported cases of PAH increased [9–19]. Hence, a consensus group of experts categorized interferon α and β as medications as possible risk factors for the development of PAH . To investigate this association further, we developed a study with the aim of determining the incidence of PAH in a national population of patients living in the USA who were treated with α and β interferon therapy.
Study design and data source
This retrospective cohort study was conducted using the Clinformatics™ Data Mart (CDM) Database (OptumInsight, Eden Prairie, Minnesota, USA), which contains data on 53 million private insurance enrollees in the USA. The database contains medical claims, pharmacy claims, and administrative data (member file) for the enrollees. Because our study was a secondary data analysis, it was classified as exempt research by the University of Texas Medical Branch Institutional Review Board (IRB).
Age, gender, region, and follow-up time were obtained from the member file. We used claims for medical services in the year prior to interferon initiation to determine comorbidities, including connective tissue disorders, liver disease other than hepatitis C, HIV/AIDS, obesity, hypertension, congestive heart failure, valvular heart disease, chronic pulmonary disease, diabetes, and sleep apnea (Appendix).
The primary outcome of interest was PAH, defined as new initiation of PAH-specific therapies following interferon therapy. The occurrence of pulmonary hypertension was identified as the first ICD-9-CM code (416.0 or 416.8) registered following interferon therapy. Among those who developed the condition, we determined whether or not they received PAH-specific therapy, including ambrisentan, bosentan, epoprostenol, iloprost, macitentan, riociguat, sildenafil, tadalafil, and treprostinil. These medications were identified using NDCs and HCPCS codes J1325, Q4080, Q4074, J3285, Q4077, J7686, S0114, and S0090.
We determined the number and proportion of study subjects with each of the aforementioned measures. We then estimated the percent of subjects developing pulmonary hypertension by the Kaplan-Meier method and presented the result in graphics. Among those with a diagnosis of pulmonary hypertension, we estimated the proportion of subjects receiving PAH-specific medications by the Kaplan-Meier method. Cox proportional hazards regression was used to examine the factors associated with pulmonary hypertension. All statistical analyses were performed using SAS version 9.3 (SAS Inc., Cary, North Carolina, USA). The significance level was set at 0.05.
Baseline characteristics of patients newly initiated on interferon therapy between 2001 and 2012
Indication for interferon
Other liver diseaseb
Chronic pulmonary disease
Connective tissue disorder
Valvular heart disease
Congestive heart failure
Atrial fibrillation and flutter
Congenital heart disease
Mean ± STD (Median)
46.36 ± 9.24 (48.00)
Follow-up time, months
29.49 ± 27.41 (20.00)
A total of 71 patients developed pulmonary hypertension during the study period, including 60 with hepatitis C and 11 with multiple sclerosis. The mean age for this group was 52.4 ± 33.5 years, with males comprising 57.7% of the cohort. Common comorbidities included chronic liver disease other than hepatitis C (42.3%), hypertension (33.8%), and diabetes mellitus (22.5%). The mean follow-up time for this group was 52.2 ± 33.5 months.
Factors associated with the likelihood of developing pulmonary hypertension
Hazard ratio (95% CI)
Indication for interferon
1.43 (0.69, 2.96)
0.26 (0.02, 4.23)
1.46 (0.19, 11.19)
2.41 (0.32, 18.29)
4.05 (0.49, 33.36)
1.02 (0.62, 1.68)
Comorbidity, Yes vs No
1.43 (0.84, 2.43)
Other liver diseasea
3.21 (1.93, 5.34)
2.27 (1.25, 4.11)
Chronic pulmonary disease
1.92 (0.82, 4.50)
1.31 (0.31, 5.56)
Connective tissue disorder
4.32 (1.71, 10.96)
0.73 (0.10, 5.51)
2.63 (0.63, 10.89)
3.76 (1.16, 12.21)
Congestive heart failure
1.10 (0.15, 8.17)
In this retrospective, administrative claims study of US patients with hepatitis C and multiple sclerosis treated with interferon, a new diagnosis of pulmonary hypertension was recognized in 71 individuals, and 7 patients were prescribed PAH-specific therapies. At first glance, the incidence appears low. However, when compared to the baseline risk in a general population, the incidence is quite substantial. To elaborate, the total person-years in our study cohort of 20,113 subjects was 49,360.5 person-years based on the follow-up time. Considering that the estimated incidence of PAH is 1.1 to 7.6 per million adults per year , we should have observed less than one PAH case in our study cohort. However, we identified 7 cases. This suggests that the risk of developing PAH in patients receiving interferon α or β therapy is several fold higher than in general population.
Several drugs and toxins have been recognized as risk factors in the development of PAH and have been categorized based on the strength of evidence as definite, likely, possible, and unlikely . Epidemiologic studies have determined a definite association between appetite suppressants as well as contaminated rapeseed oil with the development of PAH [22–24]. A consensus group of experts reviewed the evidence regarding the risk associated with development of PAH and designated α and β interferons as possible risk factors . In support of this, case reports have described new-onset PAH with interferon administration for treatment of chronic myelogenous leukemia, renal cell cancer, melanoma, chronic hepatitis, and multiple sclerosis [8–19]. Savale and colleagues described patients with newly diagnosed or worsening PAH associated with interferon therapy, from the French PAH registry . In their case series, the majority of patients received interferon for treatment of chronic hepatitis C and hemodynamic measurements were performed to confirm the diagnosis. In addition, the majority of patients carried other risk factors for PAH, namely portal hypertension and/or HIV infection. Similarly, our study represents patients with hepatitis C and multiple sclerosis treated with interferon that developed pulmonary hypertension and subsequently received PAH-specific therapies. These reports support the association of α and β interferons in the development of PAH.
There is a growing body of evidence implicating the role of inflammation and autoimmunity in the development of PAH, and this has produced work examining the role of interferons in pulmonary vascular pathology [26, 27]. Endothelin-1 is a well-established mediator in the pathogenesis of PAH and is overexpressed in patients with PAH . Elevated endothelin was found in patients receiving interferon α therapy for chronic hepatitis C, and the dependent increase in serum endothelin levels seen in these patients was related to interferon and not to the virus . A group of investigators systematically addressed the role of interferon in PAH, using in vitro and in vivo experimental models as well as clinical samples from patients with scleroderma with and without PAH . They noted that type I interferons induced endothelin-1 release from human pulmonary artery smooth muscle cells. Mice lacking functional type I interferon receptor (IFNAR1−/−) were protected from the effects of hypoxia and development of PAH. When clinical samples were analyzed, a greater number of scleroderma patients with PAH had detectable levels of interferons, along with significantly higher levels of endothelin-1, when compared to patients without PAH. Apart from elevated serum levels of interferons and endothelins, interferon receptor expression was also increased in lung sections of scleroderma patients with PAH. Thus, investigators concluded that type I interferons, their receptors, and downstream mediators are associated with PAH. Collectively, these reports provide an underlying mechanism by which type I interferon results in the development of PAH.
Our study has several limitations. An important limitation concerns the use of ICD-9 codes for the diagnosis of PAH. Prior investigations have indicated that these codes do not adequately distinguish PAH from non-PAH patients [31–33]. To address this issue, we only examined patients who were treated with PAH-specific therapies, thereby focusing on patients for whom the treating physician had sufficient evidence to prescribe PAH-specific therapies. In addition, we identified patients with continuous enrollment lacking an ICD-9 code diagnosis for pulmonary hypertension in the preceding one year. While, hemodynamic data were not available in this database, we believe that a prescription for PAH-specific therapy indicates a provider’s clinical diagnosis of PAH. We assume that an ICD code and subsequent prescription for PAH-specific therapy represents a “real world” diagnosis of PAH. Another limitation concerns the duration of follow-up. Our data was extracted from a large insurance claims database, and enrollees often discontinued their insurance policies when they switched to different employers who purchase insurance plans from other insurance carriers. Therefore, the dropout rate was high. Reports regarding interferon-induced PAH indicate that onset of the pulmonary vascular disease process may take up to 5 years, and our study may underestimate the incidence. Lastly, although our study cohort had several comorbidities that are independent risk factors for PAH, their prevalence in the cohort was much less than in general population.
Using an administrative claims database, we found that the frequency of PAH in interferon-treated hepatitis C or multiple sclerosis patients was several fold higher than that for the general US population.
The authors thank Leonard W. Pechacek for his assistance with manuscript preparations, and all the faculty and fellows from pulmonary division, University of Texas Medical Branch at Galveston, for their support.
Availability of data and materials
Data cannot be made publicly available by the authors, as they were obtained by a third party, OptumInsight. Authors may request the data from OptumInsight (link: https://www.optum.com/contact/sales-inquiry.html; phone number: 1-866-386-3404).
RP contributed to conception and design, data analysis, manuscript writing and editing; AD contributed to data analysis, manuscript drafting and editing; YLL contributed to data acquisition, data management, data analysis, manuscript editing; YFK contributed to data analysis and manuscript editing; GS contributed to the design, data analysis, manuscript drafting and editing. All authors read and approved the final manuscript.
GS reports personal fees from Sunovion Pharmaceuticals and Mylan Pharmaceuticals, outside the submitted work. Rest of the authors has nothing to disclose.
Consent for publication
Ethics approval and consent to participate
The study was classified as exempt research by the University of Texas Medical Branch Institutional Review Board (IRB).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Borden EC. Interferons: rationale for clinical trials in neoplastic disease. Ann Intern Med. 1979;91:472–9.Google Scholar
- George PM, Badiger R, Alazawi W, et al. Pharmacology and therapeutic potential of interferons. Pharmacol Ther. 2012;135:44–53.Google Scholar
- Hoofnagle JH, Mullen KD, Jones DB, et al. Treatment of chronic non-A, non-B hepatitis with recombinant human alpha interferon. a preliminary report. N Engl J Med. 1986;315:1575–8.Google Scholar
- Davis GL, Balart LA, Schiff ER, et al. Treatment of chronic hepatitis C with recombinant interferon alpha. A multicenter randomized, controlled trial. Hepatitis Interventional Therapy Group. N Engl J Med. 1989;321:1501–6.Google Scholar
- McHutchison JG, Gordon SC, Schiff ER, et al. Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. Hepatitis Interventional Therapy Group. N Engl J Med. 1998;339:1485–92.Google Scholar
- Paty D W, Li D K. Interferon beta-1b is effective in relapsing-remitting multiple sclerosis. II. MRI analysis results of a multicenter, randomized, double blind, placebo-controlled trial. UBC MS/MRI Study Group and the IFNB Multiple Sclerosis Study Group. Neurology. 1993;43:662–7.Google Scholar
- IFNB Multiple Sclerosis Study Group. Interferon beta-1b in the treatment of multiple sclerosis: final outcome of the randomized controlled trial. The IFNB Multiple Sclerosis Study Group and The University of British Columbia MS/MRI Analysis Group. Neurology. 1995;45:1277–85.Google Scholar
- Kramers C, de Mulder PH, Barth JD, et al. Acute right ventricular heart failure in a patient with renal cell carcinoma after interferon therapy. Neth J Med. 1993;42:65–8.Google Scholar
- Fruehauf S, Steiger S, Topaly J, et al. Pulmonary artery hypertension during interferon-alpha therapy for chronic myelogenous leukemia. Ann Hematol. 2001;80:308–10.Google Scholar
- Anderson P, Höglund M, Rödjer S. Pulmonary side effects of interferon alpha therapy in patients with hematological malignancies. Am J Hematol. 2003;73:54–8.Google Scholar
- Jochmann N, Kiecker F, Borges AC, et al. Long-term therapy of interferon-alpha induced pulmonary arterial hypertension with different PDE-5 inhibitors: a case report. Cardiovasc Ultrasound. 2005;3:26.Google Scholar
- Ledinek AH, Jazbec SS, Drinovec I, et al. Pulmonary arterial hypertension associated with interferon β treatment for multiple sclerosis: a case report. Mult Scler. 2009;15:885–6.Google Scholar
- Dhillon S, Kaker A, Dosanjh A, et al. Irreversible pulmonary hypertension associated with the use of interferon alpha for chronic hepatitis C. Dig Dis Sci. 2010;55:1785–90.Google Scholar
- Caravita S, Secchi MB, Wu SC, et al. Sildenafil therapy for interferon β-1a-induced pulmonary arterial hypertension: a case report. Cardiology. 2011;120:187–9.Google Scholar
- Prella M, Yerly P, Nicod LP, et al. Pulmonary arterial hypertension in patients treated with interferon. Eur Respir J. 2015;46:1849–51.Google Scholar
- Govern EM, Judge EP, Kavanagh E, Gaine S, Lynch T. Interferon β related pulmonary arterial hypertension; an emerging worrying entity? Mult Scler Relat Disord. 2015;4:284–6.Google Scholar
- Gibbons E, Promislow S, Davies RA, et al. Reversible pulmonary arterial hypertension associated with interferon-β treatment for multiple sclerosis. Can Respir J. 2015;22:263–5.Google Scholar
- Fok A, Williams T, McLean CA, et al. Interferon beta-1a long-term therapy related to pulmonary arterial hypertension in multiple sclerosis patients. Mult Scler Epub. 2016;22(11):1495–8.Google Scholar
- Baghizadeh S, Sahraian MA, Ghahari M. Reversible pulmonary artery hypertension in association with interferon-beta therapy for multiple sclerosis. Iran J Neurol. 2016;15:54–6.Google Scholar
- Simonneau G, Gatzoulis A, Adatia I, et al. Updated clinical classification of pulmonary hypertension. J Am Coll Cardiol. 2013;62(Suppl. 25):D34–41.Google Scholar
- Hoeper MM, Humbert M, Souza R, et al. A global view of pulmonary hypertension. Lancet Respir Med. 2016;4:306–22.Google Scholar
- Abenhaim L, Moride Y, Brenot F, et al. Appetite-suppressant drugs and the risk of primary pulmonary hypertension. International Primary Pulmonary Hypertension Study Group. N Engl J Med. 1996;335:609–16.Google Scholar
- Gurtner HP. Aminorex and pulmonary hypertension. A review. Cor Vasa. 1985;27:160–71.Google Scholar
- Posada de la Paz M, Philen RM, Borda AI. Toxic oil syndrome: the perspective after 20 years. Epidemiol Rev. 2001;23:231–47.Google Scholar
- Savale L, Sattler C, Gunther S, Montani D, et al. Pulmonary arterial hypertension in patients treated with interferon. Eur Respir J. 2014;44:1627–34.Google Scholar
- Eloranta ML, Franck-Larsson K, Lövgren T, et al. Type I interferon system activation and association with disease manifestations in systemic sclerosis. Ann Rheum Dis. 2010;69:1396–402.Google Scholar
- Nicolls MR, Taraseviciene-Stewart L, Rai PR, et al. Autoimmunity and pulmonary hypertension: a perspective. Eur Respir J. 2005;26:1110–8.Google Scholar
- Giaid A, Yanagisawa M, Langleben D, et al. Expression of endothelin-1 in the lungs of patients with pulmonary hypertension. N Engl J Med. 1993;328:1732–9.Google Scholar
- George PM, Cunningham ME, Galloway-Phillipps N, et al. Endothelin-1 as a mediator and potential biomarker for interferon induced pulmonary toxicity. Pulm Circ. 2012;2:501–4.Google Scholar
- George PM, Oliver E, Dorfmuller P, et al. Evidence for the involvement of type I interferon in pulmonary arterial hypertension. Circ Res. 2014;114:677–88.Google Scholar
- Hyduk A, Croft JB, Ayala C, et al. Pulmonary hypertension surveillance--United States, 1980–2002. MMWR Surveill Summ. 2005;54:1–28.Google Scholar
- Link J, Glazer C, Torres F, et al. International Classification of Diseases coding changes lead to profound declines in reported idiopathic pulmonary arterial hypertension mortality and hospitalizations: implications for database studies. Chest. 2011;139:497–504.Google Scholar
- George MG, Schieb LJ, Ayala C, et al. Pulmonary hypertension surveillance: United States, 2001 to 2010. Chest. 2014;146:476–95.Google Scholar