The possibility of reinfection has been cited by the National Institutes of Health (NIH) [10
] and the European Association for the Study of the Liver [11
] as a reason not to administer therapy for HCV infection to active IDUs. We followed-up 18 active IDUs who were successfully treated for HCV infection, 9 of whom injected drugs during the follow-up period. No more than 2 (and possibly as few as none) of the patients became reinfected as a result of illicit injection drug use after treatment for HCV infection. Patient 42 might have become reinfected, but the virus appeared only 4 months after SVR and had the same genotype as the virus responsible for the previous infection (genotype 1b, which was uncommon in our population). Late relapse may occur in 4%–10% of patients with SVR [25
]. Patient 31 reported an occupational needle stick injury and denied any illicit drug use during the 4 years since being treated for HCV infection. Although we could not document the truthfulness of her report, we have no reason to suspect that she had used injection drugs. She had worked stably and productively as a nurse for 4 years. The genotype of the virus responsible for her second infection (1a) is uncommon among IDUs in Munich but is common among other individuals with HCV infection [8
]. Thus, we estimate that the rate of reinfection among our patients was between 0–4.1 cases per 100 person-years. These findings are consistent with a Norwegian study [24
] that found a reinfection rate of 2.5 cases per 100 person-years among former IDUs (1 case of reinfection in 40 person-years of follow-up).
During treatment, the patients in our study were taught how to avoid bloodborne infections, in case they returned to using injection drugs. Addiction is a chronic, relapsing condition. Most patients entering treatment do not immediately and permanently stop using injection drugs. Relapse must be anticipated and should be planned for. Drug users may avoid acquiring and transmitting bloodborne infections when they inject drugs by using sterile injection equipment and safe injection techniques [31
]. Physicians can help IDUs to avoid acquiring HCV infection and to avoid reacquiring it after successful treatment for HCV infection by helping them to understand safe injection techniques and to gain access to sterile syringes [13
One of our patients died as the result of a drug overdose. In Germany, the mortality rate among IDUs in the first year after completion of detoxification treatment is 2.8%–10% [32
]. During methadone maintenance therapy, the mortality rate is 1.4%–2.7%, and treatment with higher doses of methadone seems to be protective [34
]. Among our patients who were successfully treated for HCV infection during the first year after detoxification, the mortality was 5.5% (95% CI, 0.1%–27.3%). These data underscore the importance of overdose prevention, which is always a critical component of the care of current and former IDUs [36
In conclusion, our data suggest that IDUs can be reinfected after treatment for HCV infection, but the reinfection rate is not so high as to jeopardize the potential benefit for most patients. Overall, 15 (30%) of the 50 IDUs we originally treated for HCV infection remained alive and HCV RNA–negative 3 years after the end of treatment. Our sample population was small; further studies with larger numbers of patients are needed. In the meantime, however, it appears that therapy for HCV infection is successful in a substantial proportion of IDUs [14
], and reinfection appears to be uncommon, even among those who inject drugs after achieving SVR. Thus, therapy for HCV infection should not be categorically withheld from IDUs [9
]. The new NIH recommendations of 2002 reflect this new standard [13
]. In our experience, the best approach for treatment of HCV infection in IDUs has been to start treatment during detoxification or methadone maintenance, with supervision by physicians specialized in both hepatology and addiction medicine.