Having cirrhosis, diabetes, or substance use disorder increased the odds of treatment discontinuation in type 1 hepatitis C virus infection, whereas use of growth factor drugs correlated with treatment persistence, reported Dr. Lauren A. Beste and colleagues in the November issue of Clinical Gastroenterology and Hepatology.
The investigators looked at 11,019 patients in the VA health care system with hepatitis C genotype 1 who received at least two prescriptions for pegylated interferon and ribavirin between Jan. 1, 2002 and Dec. 31, 2007.
Patients who completed at least 80% (38.4 weeks) of the standard 48-week treatment regimen were considered to have completed treatment; overall, 5,795 patients (52.6%) reached this goal (Clin. Gastroenterol. Hepatol. 2010 November [doi:10.1016/j.cgh.2010.07.012]).
Although "no indications currently exist for discontinuing treatment [before 12 weeks] due to lack of response," a total of 1,184 patients (roughly 10% of the total cohort) did just that, the authors said. Patients who stopped therapy before 12 weeks were significantly more likely to have cirrhosis, compared with patients who persisted with therapy (adjusted odds ratio [AOR] 1.42; P less than .01), and also were more likely to have diabetes (AOR, 1.25; P = .02) and pretreatment substance use disorder, or SUD (AOR, 1.24; P = .01).
They were also half as likely to use growth factor as were their counterparts who continued with therapy (AOR, 0.56; P less than .01). The growth factors included erythropoietin, darbepoetin, granulocyte colony-stimulating factor, and granulocyte macrophage colony-stimulating factor.
The authors also assessed patients who discontinued treatment between 12 and 24 weeks of therapy (including 317 patients with known early virologic response who discontinued despite their response). These patients were more likely to have pretreatment depression (AOR, 1.59; P less than .01), were slightly less likely to have other mental illnesses (AOR, 0.65; P = .02), and – once again – were nearly half as likely to use growth factor as were patients who persisted with the therapy (AOR, 0.64; P less than .01).
Finally, the authors looked at patients who discontinued therapy before 38.4 weeks. "No variables significantly predicted discontinuation in this time period in bivariate or multivariate analyses," wrote Dr. Beste, of the VA Puget Sound Healthcare System in Seattle, and her coauthors.
Regarding SUD as a predictor of discontinuation, the authors wrote that "patients with history of substance abuse may benefit from early support and intervention during treatment in order to continue antiviral therapy."
Of the pretreatment depression that emerged as a predictor in the 12-24 week discontinuation group, they wrote: "Prior studies report that the depressive side effects of interferon peak by week 25, which may explain the observed association between depression and discontinuation midtreatment."
And regarding the links between cirrhosis and diabetes and discontinuation, they pointed to other studies showing that these patients "may be more susceptible to treatment side-effects." However, they also speculated that blood glucose derangements in diabetic patients receiving treatment may lead to discontinuation.
Finally, Dr. Beste and her colleagues commented on the use of growth factor, which correlated with reduced risk of discontinuation both before 12 weeks and from weeks 12 to 24. They speculated that growth factor use "leads to improvement in low blood counts, allowing providers to continue treatment when otherwise it would be stopped."
Therefore, "appropriate use of growth factors should be prospectively evaluated as a modifiable means to prevent treatment discontinuation," they recommended.
Dr. Beste and her colleagues had no relevant financial disclosures. The study was supported by the Department of Veterans Affairs and the Northwest Hepatitis C Resource Center.