Validation of the Q87.11 ICD Code for Prader-Willi Syndrome

Area of Science:

• Medical Informatics
• Genetics
• Rare Diseases

Background:

• Prader-Willi syndrome (PWS) is a rare genetic disorder.
• The ICD-10 code Q87.11 is used for PWS identification in large studies.
• The diagnostic validity of the Q87.11 code has not been previously evaluated.

Purpose of the Study:

• To assess the accuracy and diagnostic validity of the ICD-10 code Q87.11 for identifying individuals with Prader-Willi syndrome.
• To evaluate the performance of the Q87.11 code at both individual and encounter levels.

Main Methods:

• Reviewed electronic health records (EHR) of patients with the Q87.11 code.
• Assessed a sample of patients with free-text evidence of PWS but no code.
• Conducted expert chart reviews to confirm PWS diagnosis.
• Calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Main Results:

• Of 2,718,218 patients, 126 had the Q87.11 code, with 122 confirmed PWS cases (PPV 96.8%).
• Code sensitivity was estimated at 92.4%, with 100% specificity and NPV.
• Per-encounter sensitivity was 79.4% for inpatient and 46.0% for outpatient visits.

Conclusions:

• A single use of the Q87.11 code shows excellent overall accuracy for identifying PWS patients.
• The code's validity is supported for use in analyzing administrative claims datasets.
• While accurate, sensitivity varies between inpatient and outpatient encounters.