Identification of the risk factors for complex-multiple long-term conditions (C-MLTC): A scoping review

Background Complex multiple long-term conditions (C-MLTC) are commonly defined as the presence of four or more long-term conditions, and their prevalence is projected to increase significantly over the next decade. Methods We conducted a scoping review of the literature to identify available evidence on risk factors for C-MLTC and map potential clusters. We focused on a subset of 18 chronic conditions because they are among the most commonly reported and prevalent in the general population. For guidelines, we searched the NICE Clinical Knowledge Summaries (CKS), and for systematic reviews, we searched PubMed, Google Scholar, and the TRIP database. Results We found 53 risk factors associated with 18 long-term conditions. Sixteen of these are linked to C-MLTC, of which 11 are modifiable. Although we reviewed 55 systematic reviews, inconsistent reporting made it difficult to quantify the risk factors and conditions associated with C-MLTC. Diabetes mellitus was a risk factor for most other conditions (n=10), followed by coronary heart disease, hypertension, and chronic kidney disease (each associated with eight long-term conditions). Additionally, depression and anxiety were commonly associated with long-term conditions. Conclusion Several risk factors and conditions contribute to the development of multimorbidity. Anxiety and depression are associated with nearly all long-term conditions. Reporting problems in the existing evidence and a lack of clear definitions prevent adequate quantification of the risks associated with C-MLTC.