Extended-therapy duration for chronic hepatitis C, genotype 1: The long and the short of it

Table 1 Studies of extended therapy for treatment-naive, genotype 1-infected slow responders to pegylated interferon with ribavirin

Country(ies) in which studies performed	Number of subjects studied	Treatment duration (wk)	Definition of slow response (assay sensitivity)	Pegylated interferon type and weekly dose	Ribavirin daily dose (mg)	End-of-treatment responses	Relapse rates	Sustained virologic response rates	P value (sustained response)	Major study limitation (s)
Spain, Israel[27]	8	72	≥ 2-log10 12 wk decrease1 (100 IU/mL)	Alpha -2b 1.0 mcg/kg	800	100%	13%	88%	Not applicable	Few subjects suboptimal ribavirin dose
	Germany[28]	100			48	> 50 IU/mL at wk 12 (50 IU/mL)	Alpha 2-a 180 mcg	800	47%		64%	17%	0.04	Retrospective subgroup analysis suboptimal ribavirin dose
106		72		49%	40%			29%
Spain[29]	149	48	> 50 IU/mL at wk 4 (50 IU/mL)	Alpha 2-a 180 mcg	800	58%	53%	28%	0.003	Suboptimal ribavirin dose
	142	72				62%	17%	44%
United States[30]	49	48	≥ 2-log10 12 wk decrease1 (10 IU/mL)	Alpha 2-b 1.5 mcg/kg	800-1400	45%	59%	18%	0.03	Single center
	52	72				48%	20%	38%
Europe[3536]	252	48	≥ 2-log10 12 wk decrease1 (50 IU/mL)	Alpha 2-a 180 mcg	1000–1200	Not available	32%	52%	Not available	Few subjects some genotype four infections
	162	72					18%	69%
Italy[37]	21	48	≥ 2-log10 12 wk decrease1 (50 IU/mL)	Alpha -2b 1.5 mcg/kg or Alpha -2a 180 mcg	1000-1200	5%3	100%3	0%3	0.34	Subgroup analysis
	52	72				19%	60%	8%
Europe, Canada, Israel[38]	63	48	≥ 2-log10 12 wk decrease1 (30 IU/mL)	Alpha -2b 1.5 mcg/kg	800-1400	Pending	Pending	Pending	Pending	Pending
	63	72

¹Detectable viremia at 12 wk and undetectable viremia at 24 wk required;

²Less than 10% genotype 4 infections;

³One of twenty patients had an end-of-treatment response, but relapsed;

⁴Not statistically significant.