Predicting the risk of amputation and death in patients with diabetic foot ulcer. A long‐term prospective cohort study of patients in Tanzania

Introduction
This prospective cohort study aimed to identify the characteristics of patients with diabetic foot ulcer who are at higher risk of amputation and at increased risk of death.

Methods
About 103(M/F:60/43) participants, with active foot ulcer at baseline, participated in this study and followed for 22 years till death or lost to follow-up. Ten clinical measures were collected at baseline. During the follow-up of 4.2 ± 5.4 years, 22(M/F:14/8) participants had an amputation and 50(M/F:32/18) participants passed away during 5.5 ± 5.8 years follow-up period.

Results
Cox Proportional Hazard regression (HR[95%CI]) indicated neuropathy (6.415[1.119–36.778]); peripheral arterial disease (PAD) (9.741[1.932– 49.109]); current smoking (16.148[1.658–157.308]); diabetes type- 1 (3.228[1.151–9.048]) and longer delay attending appointment after ulcer (1.013[1.003–1.023]) were significantly (p < .05) associated with increased risk of amputation. In addition, death was significantly associated with the risk of amputation (3.458[1.243–9.621]). Three parameters (HR[95%CI]) including neuropathy (3.058[1.297–7.210]); PAD (5.069[2.113–12.160]); amputation history (3.689[1.306–10.423]) and retinopathy (2.389[1.227–4.653]) were all significantly associated with increased risk of death. Kaplan–Meier survival analyses indicates that the time to amputation in years for participants who eventually died was significantly shorter (11.122 ± 1.507) vs those who stayed alive (15.427 ± 1.370).

Conclusion
Neuropathy and PAD were the only two characteristics that increased both the risk of amputation and death. Amputation showed to contribute to an increased risk of death and those participants who eventually died had a higher risk of amputation. Delay in attending appointments after ulceration is shown to increase the risk of amputation. In addition, the participants with PAD showed a significantly shorter time to both amputation and death while neuropathy was only associated with decreased time to death. Amputation history and death during follow-up decrease the time to death and amputation respectively.