Association of infrapopliteal medial arterial calcification with lower-limb amputations in high-risk patients: A systematic review and meta-analysis

Medial arterial calcification (MAC) is a known risk factor for cardiovascular morbidity. The association between vascular calcifications and poor outcome in several vascular districts suggest that infrapopliteal MAC could be a risk factor for lower-limb amputation (LLA). This study's objective is to review the available literature focusing on the association between infrapopliteal MAC and LLA in high-risk patients. The PubMed and Embase databases were systematically searched. We selected original studies reporting the association between infrapopliteal MAC and LLAs in patients with diabetes and/or peripheral artery disease (PAD). Estimates were pooled using either a fixed-effects or a random-effects model meta-analysis. Heterogeneity was evaluated using the Q and I-2 statistics. Publication bias was investigated with a funnel plot and Egger test. The trim-and-fill method was designed to estimate the possibly missing studies. Influence analysis was conducted to search studies influencing the final result. Test of moderators was used to compare estimates in good versus non-good-quality studies. Fifteen articles satisfied the selection criteria (n = 6489; median follow-up: 36 months). MAC was significantly associated with LLAs (pooled adjusted risk ratio (RR): 2.27; 95% CI: 1.89-2.74; I-2 = 25.3%, Q-test: p = 0.17). This association was kept in the subgroup of patients with diabetes (RR: 2.37; 95% CI: 1.76-3.20) and patients with PAD (RR: 2.48; 95% CI: 1.72-3.58). The association was maintained if considering as outcome only major amputations (RR: 2.11; 95% CI: 1.46-3.06). Our results show that infrapopliteal MAC is associated with LLAs, thus suggesting MAC as a possible new marker of the at-risk limb.