Endocrine Abstracts

Background: Hereditary hypophosphatemia (HH) are rare diseases, characterized by excessive renal phosphate wasting and inappropriately low 1,25-dihydroxy-vitamin D causing hypophosphatemia. In children, the disease manifests as rickets and osteomalacia, in adults osteomalacia. Complications from the disease appear with increasing age, in adults characterized by pain, arthrosis, persisting deformities of long bones if not corrected during childhood causing compromised functions of daily living and decreased health-related quality of life.

Aim: In this study, we aimed to investigate if patients with HH achieved the same educational level as the background population and if the ability to work with increasing age was comparable.

Methods: The case population was identified in the Danish National Patient Register based on five diagnosis codes referring to rickets or hypophosphatemia. A journal audit was performed based on all cases identified in Region of Midt Jutland and on available medical files from the remaining four regions in Denmark to verify the diagnosis of HH based on predefined diagnostic criteria. The background population (control) matched by gender, birth year and month, was randomly selected using the Danish Civil Registration System matching fifty controls to each patient with HH. Data on highest educational attainment and employment information were retrieved from the Educational Register and the Ministry of Employments database, respectively.

Results: The dataset comprised 120 patients with HH matched with 6000 controls. We found no difference in the highest obtained educational level between patients with HH compared to controls. A significantly lower proportion of patients with HH aged 40–49y were employed compared to controls (P=0.012), and a significantly larger proportion aged 30-49y were in flexible job, in rehabilitation or on flexible benefits compared with controls (P<0.05). From age 60+y, a significantly larger proportion of controls were unemployed (P<0.001). There was no difference in early retirement in age groups 18–29y, but from age 30–59y, a significantly larger proportion of patients with HH were early retired (P<0.05). The mean age at early retirement was 38.7y for patients with HH compared to 45.1y for controls (Δ 6.4y, P=0.015).

Conclusion: Patients with HH achieved a comparable educational level compared with the background population, but a significantly larger proportion of patients with HH had the need for a flexible job, rehabilitation or flexible benefits in addition to early retirement. There is a need for identifying and addressing the possible causes for well-educated patients with HH leaving working life too early.