[Survival analysis in hepatitis C cases aged ≥18 years in Yuxi City from 2005 to 2023]

To analyze all-cause mortality among hepatitis C cases aged ≥18 years in Yuxi City from 2005 to 2023 and explore the interactions of factors influencing survival time. Baseline and follow-up data for hepatitis C cases reported during this period were extracted from the Chinese National Notifiable Disease Reporting System. Survival time and related factors were assessed using the Cox proportional hazards model. Kaplan-Meier cumulative mortality risk curves were generated for treated and untreated hepatitis C cases, and interactions among subgroups of various influencing factors were examined. A total of 5 110 hepatitis C cases aged ≥18 years were reported from 2005 to 2023, encompassing 35 349.25 person-years of observation with the follow-up time duration M (Q₁, Q₃) was 6.17 (2.33, 11.08) person-years. There were 763 all-cause deaths, corresponding to a mortality density of 2.16 per 100 person-years. Survival analysis showed a statistically significant difference in cumulative mortality between the treated and untreated groups (Log-rank χ²=122.033, P<0.001), with a lower risk of death observed among treated patients. Additive model analysis showed that there was a synergistic interaction between treatment status and age group, with relative excess of interaction, attributable proportions of interaction, and synergy index of 6.16 (95%CI: 2.70-9.61), 1.83 (95%CI: 1.46-2.30), and 0.42 (95%CI: 0.31-0.53), respectively; and between treatment status and gender. There was a synergistic interaction between treatment status and sex, with relative excess of interaction, attributable proportions of interaction, and synergy index of 2.63 (95%CI: 1.14-4.13), 1.56 (95%CI: 1.19-2.06), and 0.32 (95%CI: 0.17-0.46), respectively. The cause of death composition were 38.53% (249 cases) attributed to hepatitis C-related causes.The leading non-hepatitis C-related causes of death were cardiovascular and cerebrovascular diseases, pulmonary diseases, malignancies, drug overdose, and injuries. In conclusion, hepatitis C cases ≥18 years of age in Yuxi City had a lower cumulative mortality rate when treated than when untreated. Treatment status interacted with age and gender on patient survival, respectively. Changes in patients with concomitant cardiovascular diseases, pulmonary diseases and malignancies should be focused.