In patients with iron deficiency anemia (IDA), intravenous iron (IVI) is the preferred and most efficacious treatment when oral iron cannot be used or where rapid iron delivery is required; however, IV infusions are burdensome for patients and require them to travel to specialist infusion units, which can have a detrimental effect on patient quality of life (QoL). Also, the number of visits varies greatly between different IVI formulations. The aim of the present study was to quantify the magnitude of the effect of different annual infusion rates on QoL.

METHODS

A recent time trade-off (TTO) study with 1,091 respondents in China reported mean utility values for patients receiving 1, 2, 5, and 7 IVI infusions per year, each lasting 30-60 minutes. Using one infusion as a baseline, the R “lm” function was used to perform a linear regression with the log-transformed incremental infusions as the predictor of the log-transformed incremental disutility. Exponentiation of the model yielded a model of the form U = αx^β where U is the overall annual disutility, x the annual number of infusions, and α and β the coefficients from the linear regression.

RESULTS

The linear regression resulted in a model of the form U = 0.016x^0.3922. Increasing the number of annual IVI infusions from one to two would result in an incremental disutility of 0.005, while increasing the number of annual IVI infusions from six to seven would result in an incremental disutility of 0.002.

CONCLUSIONS

Diminishing marginal disutility models are designed to capture the phenomenon of patients adapting to events that occur more frequently, with the negative effect of each additional event diminishing as the event frequency increases. The present model utilized TTO data from a large population of Chinese patients to quantify this phenomenon with regard to IVI infusions.