In this Danish case-control-study that included >1200 cases over 4 decades, certain comorbidities increased risk of invasive meningococcal disease, ranging from a 2- to 40-fold increased risk. Vaccination and increased focus on appropriate medical care may be warranted in these populations.

Background Risk of invasive meningococcal disease (IMD) is increased in patients with complement deficiency and human immunodeficiency virus (HIV) infection. Risk associated with comorbidity is not well described. Methods This was a nationwide adult case-control study. Cases for the period 1977-2018 were identified by the national meningococcus reference laboratory. Matched controls were identified by registry linkage. Comorbidities diagnosed prior to IMD were based on the International Classification of Diseases, Eighth or Tenth Revision. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by logistic regression after adjustment for sex, age, and other comorbidities. Results We identified 1221 cases (45% male), with a median age of 45 years (interquartile range, 22-64 years). The dominant meningococcal serogroups were B (n = 738) and C (n = 337). Increased risk of IMD was associated with solid organ transplantation (SOT) (OR 40.47 [95% CI: 4.84-337.23]), hemolytic anemia (OR 7.56 [95% CI: 2.63-21.79]), renal disease (OR 2.95 [95% CI: 1.77-4.92]), liver disease (OR 2.54 [95% CI: 1.58-4.08]), cancer (OR 2.31 [95% CI: 1.85-2.89]), diabetes (OR 1.74 [95% CI: 1.27-2.39]), neurological disease (OR 1.72 [95% CI: 1.20-2.46]), and autoimmune disease (OR 1.70 [95% CI: 1.63-2.11]). Having 1, 2, and >= 3 comorbidities was associated with increased risk of IMD (ORs 1.6-3.5). Increased risk was not associated with specific serogroups. Conclusions This study of adults with IMD over 4 decades showed increased risk of IMD associated with renal disease, immunological disorders, liver disease, cancer, and SOT ranging from a 2- to 40-fold increased risk. Vaccination may be warranted in these populations.