Endocrine Abstracts

Hypoparathyroidism is a rare endocrine disorder characterized by insufficient parathyroid hormone levels in the blood, low serum calcium and elevated serum phosphate. Studies evaluating the prevalence of chronic hypoparathyroidism (cHypoPT) are limited, and it is challenging to compare prevalence estimates owing tothe rarity of the disease and the difficulty of differentiating transient from permanent or cHypoPTin secondary data analyses. PublishedcHypoPTprevalence is between 9–37/100,000 from population-based studies in five countries. The objective of the study was to develop and evaluate two models that can estimate the prevalence of cHypoPTfor countries where population-based data are unavailable. We developed a thyroid surgery-derived model using data on thyroid cancer prevalence and probability of cHypoPT following thyroid surgery for countries where the relevant inputs were available from publishedliterature. We estimated the lifetime prevalence of thyroid cancer using historical cancer incidence data from cancer incidence registries and assumed most thyroid cancer cases undergo surgical resection. Using country-specific ratios of cancer-related versus non-cancer-related thyroid surgeries, we calculated lifetime prevalence of thyroid surgery. The proportions of thyroid surgeries leading to cHypoPT were applied to estimate the prevalence of surgical-related cHypoPT. Lastly, we summed up estimates of the prevalence of non-surgical and surgical-related cHypoPT. We considered gross domestic product (GDP) as a proxy for important risk factors for cHypoPT: healthcare quality and access, surgeon technique/skill, follow-up care and complication rates. We identified published population-based estimates for cHypoPTprevalence for five countries; the corresponding country-specific GDP data were collected from the World Bank. We evaluated the correlation between GDP and chronic hypoparathyroidism prevalence using R² and exponential coefficient values. We used this correlation to model country-specific prevalence and compared estimates from both models with published prevalence estimates. cHypoPTprevalence strongly correlated with GDP (R² = 0.86; P<0.001). Prevalence estimates obtained from both modelswere comparable. For the United States, the thyroid surgery-derivedprevalence was 22.8 per 100,000, comparable to the prevalence of ~23.2 that was calculated from published population-based estimates and 20.6 for the GDP-based model. In the absence of population-based studies, thyroid surgery-derived and GDP-based models can be used to estimate the prevalence of cHypoPT. These two methods yielded comparable US prevalence estimates and accurately predicted US prevalence as reported in the literature. Further validation is required, but preliminary data suggest that these models can be used to predict prevalence in countries without population-based studies.

Funding: Shire, a Takeda company