OC 54.4 - Multimorbidity a novel risk factor for venous thromboembolism

Background: Multimorbidity, i.e. two or more non-communicable diseases (NCDs), has become an increasing burden for society and healthcare. Venous thromboembolism (VTE) is a common and potentially lethal disease. The association between multimorbidity and VTE has previously been shown but the association with incident VTE remains unknown.

Aims: To investigate whether there is an association between multimorbidity and its severity and incident VTE using landmark analysis.

Methods: A cohort study using landmark analysis of 2694442 unique individuals between 1997-2015. By linking Swedish national registers three landmarks (L1, L2, L3) were created with 14, 9 and 4 years follow up time. At baseline for each landmark inclusion criteria were no previous VTE. A list of 45 NCDs was used to determine multimorbidity, i.e. two or more NCDs. Increasing numbers of NCDs (0-≥5) marked multimorbidity severity. Hazard ratio (HR) with 95% confidence interval (CI) for VTE was computed and adjusted for sex, education, year of birth. Death and emigration were treated as competing event.

Results: Descriptive findings for unique individuals are shown in Table 1. Females were more often multimorbid. Multimorbidity was more prevalent among elderly and those with lower education. Adjusted HR for VTE in L1 analysis was 2.47 (95%CI 2.24-2.72), in L2 analysis was 2.23 (95%CI 2.11-2.36), and in L3 analysis was 2.16 (95%CI 2.03-2.29). HR increased with multimorbidity severity. HR for multimorbidity with 5 or more NCDs was 4.29 (95%CI 2.53-7.28) in L1 analysis, 4.45 (95%CI 3.64-5.45) in L2 analysis and 4.83 (95%CI 4.20-5.55) in L3 analysis (Table 1). Cumulative incidence and Kaplan-Meier survival estimates are presented in Figure 1 according to multimorbidity score.

Conclusion(s): Multimorbidity is associated with incident VTE. Moreover, VTE incidence increase with multimorbidity severity. Multimorbidity is a novel dose-graded predictor for VTE. Further studies will determine the usefulness for VTE prediction in different clinical settings.