Örebro Studies in Medicine

Härtill 4 uppsatser Diss. (sammanfattning) Örebro : Örebro universitet, 2009 Doctor medicinae Wilandersalen, Universitetssjukhuset, Örebro The hepatitis C virus (HCV) was characterised in 1989. HCV was transmitted through transfusion of blood/blood products, but injection drug use is now the most common route of transmission. The infection is usually asymptomatic but becomes chronic in about 75%, and in 20 years 15-25% develops liver cirrhosis, with a risk for liver failure and liver cancer. HCV has also been associated with lymphoproliferative disorders. The aim of this thesis was to study morbidity and mortality in a national, population-based cohort of HCV-infected individuals. The study population consisted of all persons with a diagnosed HCV-infection recorded in the national surveillance database. This file was linked to other national registers to obtain information of emigration, deaths, cancers, and inpatient care. All personal identifiers were removed before analysis. In Paper I the standardized incidence ratios (SIR) for Hodgkin’s and non-Hodgkin’s lymphoma (NHL), multiple myeloma, acute and chronic lymphatic leukaemia, and thyroid cancer were studied. In the HCV-cohort (n: 27,150) there was a doubled risk for NHL and multiple myeloma in patients infected for more than 15 years, compared with the general population (age-, sex- and calendar-year specific incidence rates). The results strengthened these earlier controversial associations. The SIR and also the absolute risk for primary liver cancer were estimated in Paper II . In the HCV-cohort (n: 36,126) the individuals infected for more than 25 years had a more than 40 times increased risk for liver cancer compared with the general population. The absolute risk of primary liver cancer was 7% within 40 years of HCV-infection. Mortality and cause of death were studied in Paper III. The standardized mortality ratio (SMR) demonstrated a 5.8 times excess mortality in the HCV-cohort (n: 34,235) compared with the general population, and a 35.5 times excess mortality from liver disease. Deaths from illicit drugs and external reasons were common in young adults. Paper IV presents a study of inpatient care. The HCV-cohort (n: 43,000) was compared with a matched reference population (n: 215,000). Cox regression was used to estimate the likelihood, a hazard ratio, for admission to hospital, and frequencies and rates to estimate the total burden. In the HCV-cohort inpatient care was high and about 50% was ps