Online tool predicts who’s at risk for chronic complication after surgery
3 factors can be used to identify patients at risk of persistent hypoparathyroidism
A new predictive model can now accurately identify which patients are at high risk of developing persistent hypoparathyroidism, a chronic complication of thyroid surgery, soon after the operation.
Research from the Netherlands indicates that three simple clinical factors can be entered into an online-accessible model to estimate the probability of this long-term condition: a drop in parathyroid hormone (PTH) and corrected calcium levels on the day after surgery, and the failure to identify at least one parathyroid gland during the procedure.
Because persistent hypoparathyroidism leads to a worse quality of life and increases the risk of adverse events and hospital readmissions, this new tool could be vital for doctors to provide personalized care and prevent complications.
The study, “Development and Validation of a Prognostic Model for Persistent Hypoparathyroidism After Total or Completion Thyroidectomy,” was published in the journal Clinical Otolaryngology.
What is hypoparathyroidism?
Hypoparathyroidism refers to a condition characterized by low levels of parathyroid hormone (PTH), a hormone produced by the parathyroid glands located in the neck, near the thyroid gland. When PTH levels fall too low, calcium levels drop abnormally, leading to various disease symptoms.
In many cases, hypoparathyroidism is caused by accidental damage to the parathyroids during surgery to remove all or part of the thyroid gland in the neck, a procedure called a thyroidectomy.
While most people recover parathyroid function within a few weeks after surgery, some will develop hypoparathyroidism that lasts at least one year, a condition known as persistent or chronic hypoparathyroidism.
Because these patients tend to have a worse quality of life, identifying who is at risk of persistent hypoparathyroidism soon after surgery is essential to prevent adverse events and hospital readmissions.
To address that, researchers in the Netherlands set out to develop a model to predict persistent hypoparathyroidism after a thyroidectomy. The team collected data on 366 adult patients, two-thirds (68%) of whom were women, who had undergone a thyroidectomy at 12 hospitals in the Netherlands.
Most patients (80%) underwent a total thyroidectomy, or the removal of the entire thyroid gland. The remaining underwent a completion thyroidectomy, or the removal of the remaining thyroid tissue after a previous partial thyroidectomy. Blood samples were drawn starting within 24 hours of the surgery.
Persistent hypoparathyroidism, defined here as the need for vitamin D supplementation one year after surgery and the inability to reduce and discontinue vitamin D, was noted in 12% of patients.
High-risk factors and predictive accuracy
According to the analysis, failure to identify at least one parathyroid gland during surgery increased the risk of persistent hypoparathyroidism by more than four times. A change in PTH levels within a day of surgery was associated with a 10% increased risk, while corrected calcium levels were associated with a 54% increased risk of persistent hypoparathyroidism.
When these factors were included in a final model, the tool had an excellent ability to distinguish between high- and low-risk patients, with a C-index of 0.88. This metric, which ranges from 0.5 to 1.0, measures a model’s ability to correctly rank risks, with higher values indicating better predictive performance.
The C-index remained higher after excluding groups of patients from different time periods and locations across the Netherlands. The model also demonstrated a high discriminative ability for predicting readmissions within the first 30 days after discharge due to low calcium levels, with a C-index of 0.85.
“The model developed in this study facilitates a quick individual assessment of patients at risk for persistent hypoparathyroidism after total thyroidectomy and could aid in personalised discharge instructions and supplementation regimens,” the researchers concluded. “External validation of the model proposed in this study is required to determine its usefulness in other patient populations.”
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