Evaluating More Accurate Quality of Life Measurement Instruments in X-Linked Hypophosphatemia

According to an article in the Ophanet Journal of Rare Diseases, submitted by Javi Jandhyala, generic quality of life (QoL) instruments, like EuroQoL-5D (EQ-5D), are “increasingly being accepted as imprecise, especially in rare diseases, based on the relevance of their indicators.” As such, Jandhyala assessed the ability of an interview-based QoL assessor, the Schedule for the Evaluation of Individual Quality of Life-Direct Weighting (SEIQoL-DW), to detect changes in QoL both at baseline and in follow-up visits in eleven participants with X-Linked Hypophosphatemia (XLH). The article reported that “EQ-5D and SEIQoL-baseline cues [SEIQoL-BC] failed to detect the same statistically significant decrease in QoL observed by SEIQoL-visit cues [SEIQoL-VC].”

Further, the article relayed that “both sets of SEIQoL observations were more closely associated with each other than with EQ-5D,” and ultimately presented the conclusion that “observing constructs such as QoL in rare diseases benefits from a Neutrality in indicator selection and respecting variation in dominance of various indicators over time.”

In the study, all QoL scores decreased from baseline by 13.36% for SEIQoL-VC, 7.32% for SEIQoL-BC, and 2.7% for ED-5Q. Additionally, the QoL score decrease was only statistically significant for the SEIQoL visit scores (p = 0.037). After baseline assessment, the authors noted that the only highly positive and statistically significant pairwise association was between SEIQoL-VC and SEIQoL-BC at six months (ρ = 0.782; p <0.05) and nine months (ρ = 0.879; p  <0.05).

Ultimately, Jandhyala proposed that the study’s results “showed that EQ-5D is not an appropriate tool to monitor change in adult XLH patients over time,” and that “SEIQoL’s Neutrality in indicator selection is limited to the five most important domains which change over time,” advantaging it in XLH and potentially other rare diseases.