Hypophosphatemia attenuates improvements in vitality after intravenous iron treatment in patients with inflammatory bowel disease

Abstract

Purpose: Iron deficiency anemia is common in people with inflammatory bowel disease (IBD), causing deterioration in quality of life, which can be reversed by treatment that increases iron stores and hemoglobin levels. The present post hoc analyses estimate health state utility values for patients with IBD after treatment with ferric derisomaltose or ferric carboxymaltose and evaluate the health domains driving the changes.

Methods: SF-36v2 responses were recorded at baseline and day 14, 35, 49, and 70 from 97 patients enrolled in the randomized, double-blind, PHOSPHARE-IBD trial (ClinicalTrials.gov ID: NCT03466983), in which patients with IBD across five European countries were randomly allocated to either ferric derisomaltose or ferric carboxymaltose. Changes in SF-36v2 scale scores and SF-6Dv2 health utility values were analyzed by mixed models.

Results: In both treatment arms, SF-6Dv2 utility values and all SF-36v2 scale scores, except Bodily Pain, improved significantly (p = < 0.0001). The improvement in SF-6Dv2 utility values showed no significant treatment group difference. The improvement in utility values was completely explained by improvement in Vitality scores. Vitality scores showed significantly larger improvement with ferric derisomaltose versus ferric carboxymaltose (p = 0.026). Patients with the smallest decrease in phosphate had significantly larger improvements in Vitality scores at each time point (p = < 0.05 for all comparisons) and overall (p = 0.0006).

Conclusions: Utility values improved significantly with intravenous iron treatment. Improvement in utility values was primarily driven by Vitality scores, which showed significantly greater improvement in the ferric derisomaltose arm. Smaller decreases in phosphate were associated with significantly higher Vitality scores, suggesting that quality of life improvement is attenuated by hypophosphatemia. The utility values can inform future cost-utility analysis.

Keywords: Administration; Inflammatory bowel diseases; Intravenous; Iron; Iron deficiency anemia; Quality of life.

Fig. 1

Changes in SF-6Dv2 scores over time by IV iron treatment. Estimated mean score and 95% confidence intervals. P values calculated based on the comparison between treatment groups in the change from baseline to each follow-up

Fig. 2

Changes in SF-36v2 Vitality scores over time by IV iron treatment—estimated mean score and 95% confidence interval. Estimated mean score and 95% confidence intervals. P values calculated based on the comparison between treatment groups in the change from baseline to each follow-up

Fig. 3

Improvement in SF-6Dv2 score from baseline across the two treatment arms, without and with control for individual SF-36v2 health domain scales. Estimate and 95% confidence interval. No control: estimated SF-6Dv2 score improvement from baseline at 14, 35, 49, and 70 days of follow-up. PF through MH: estimated SF-6Dv2 score improvement from baseline at 14, 35, 49, and 70 days of follow-up with control for each of the eight corresponding SF-36v2 health domain scales; PF: Physical Functioning; RP: Role Physical; BP: Bodily Pain; GH: General Health; VT: Vitality; SF: Social Functioning; RE: Role Emotional; MH: Mental Health

Fig. 4

Least squares mean change (95% CI) from baseline in SF-36v2 Vitality score by s-phosphate mean change quartiles (safety analysis set). Estimates from mixed model for repeated measures with phosphate change group (quartiles), day, and stratum as factors, day-by-phosphate change group and day-by-baseline value interactions, and baseline value as covariate. For each patient, the average change from baseline phosphate was calculated using only observed values and ignoring number of post-baseline measurements. Between-quartile values indicated: *p < 0.05; **p = 0.001–0.01; ***p < 0.001