In this retrospective analysis of hepatitis C therapy in ordinary clinical practice at three Norwegian hospitals, we found that 70 % of the patients achieved SVR after combination treatment with pegylated interferon and ribavirin. Response to treatment was strongly correlated with the patient's age: the later in life treatment was administered, the more difficult it was to achieve SVR.
This is the largest Scandinavian study of the effect of hepatitis C treatment. It shows good results for treatment compared with other reports from clinical practice. A large Danish dataset from 2011 showed SVR rates for genotypes 1, 2 and 3 infection of 44 %, 74 % and 71 %, respectively (9). The corresponding figures for our dataset were 57 %, 77 % and 78 %. A smaller dataset from Haukeland University Hospital yielded SVR rates of 44 % for genotype 1 and 75 % for genotype 3 (only two with genotype 2) (10). By way of comparison, an Australian prospective multi-centre study from 2012 referred to a sustained virological response rate of 50 % for genotype 1 and of 70 % for genotypes 2 and 3 (17). Corresponding figures from a French retrospective study were 34 %, 58 % and 52 % for genotypes 1, 2 and 3, respectively, analysed according to an intent-to-treat protocol (18). By way of comparison, past approval studies have shown 46 – 52 % SVR for genotype 1 and 76 – 84 % for genotypes 2 or 3 (7, 8).
Our data show that the older the patient, the more difficult it is to achieve SVR with interferon-based therapy. We found 83 % lower SVR, irrespective of genotype, in patients over the age of 50 than in patients who were treated before the age of 30. With genotypes 2 and 3, SVR fell from 91 % in patients aged 30 or less to 61 % in those over 50.
We believe that the high percentage of patients in our dataset who achieve SVR is due to the fact that the patients were younger than those treated in other countries. The median age at the start of treatment was 46 in the Danish population, while the median age at the start of treatment was 39 in our study. Increasing age in itself results in reduced sensitivity to interferon. In addition the degree of fibrosis increases with age, and will contribute to lower SVR rates (14, 19).
In our study there are quite large variations in the rates of SVR between the Norwegian hospitals. The rate was 63 % for genotype 1 at Stavanger University Hospital compared with 48 % at Akershus University Hospital. Similarly, the average age at the start of treatment for patients with genotype 1 was 38 and 45, respectively, for the two populations. After correcting for age, we found no difference in response to treatment between the hospitals.
Whereas it has been the general consensus that all patients with genotypes 2 or 3 should receive treatment, there has been less consensus on the indication for treatment of patients with genotype 1 (16). Because the course of hepatitis C is benign in many, and the adverse reactions associated with 48 weeks of pegylated interferon are substantial, the doctors at Akershus University Hospital have generally elected to watch and wait, and only treated those with severe liver fibrosis and/or substantial inflammation. The choice made at Stavanger University Hospital and Østfold Hospital has often been to treat everyone who is motivated, because young people with little liver damage respond better to treatment.