['Clinical trials provided conflicting results about whether extended duration of treatment with pegylated interferon-alfa (pegIFN-alfa) and ribavirin (more than 48 weeks) improves rates of sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) genotype 1 and slow virologic response. We performed a meta-analysis to determine the overall impact of extended treatment, compared with standard treatment, on virologic response rates in these patients.', 'We performed a literature search to identify randomized controlled trials (RCTs) that included monoinfected, treatment-naive patients infected with HCV genotype 1; data were compared between slow responding patients treated with pegIFN-alfa-2a/b plus ribavirin for 48 weeks and those that received extended treatment (as much as 72 weeks). End points included SVR rates, end-of-treatment (EOT) response and relapse rates; they were calculated according to the DerSimonian-Laird estimate.', 'Six RCTs assessed the benefits of extended treatment with pegIFN-alfa-2a/b and ribavirin in treatment-naive patients with HCV genotype 1 that were slow responders (n = 669). The extended treatment significantly improved SVR rates in slow responders, compared with the standard of care (14.7% increase in overall SVR; 95% confidence interval, 4%-25.5%; P = .0072). Rates of viral relapse were significantly reduced by extended treatment, but EOT response rates were similar. The frequency of voluntary treatment discontinuation, but not of serious adverse events, was significantly increased by extended therapy.'] Does meta-analysis show extended therapy improves response of patients with chronic hepatitis C virus genotype 1 infection?