The aim of this study was to determine an adherence-based risk equation that estimates the annual risk of developing IOL-related complications for any ICT in patients with TDT.

METHODS: A literature search was conducted for publications reporting the risk of IOL-related complications in relation to adherence.

RESULTS: None of the articles described the full risk equation used in their model or study. Therefore, the findings and assumptions from three publications were combined into one risk equation: IOL compl (other trt)=IOL compl(DFO)*(1-rr)^((Ad(other trt)-Ad(DFO))*100)

IOL compl = annual risk of IOL related complications in %, other treatment (trt) = DFX, DFP, DFO/DFP, Ad = adherence in %, rr = risk ratio in %

We assumed a baseline IOL-related complication rate under ICT. DFO was selected as the reference treatment, as published adherence rates and associated complication rates were available. To estimate the IOL-related complication rate for other treatments, the baseline rate was adjusted by the adherence-dependent risk ratio. This risk ratio was complication specific and, with each percentage point increase in adherence, the complication rate was reduced by the risk ratio.

CONCLUSIONS: Risk equations are often used in models, but rarely published. This equation can be used for future economic evaluations of ICT using adherence rates from clinical trials or real-world settings. Further validation of the equation is needed.