What question did this study set out to answer?

This study aims to evaluate the accuracy of ICD-10 codes for diagnosing hypertensive crises among older adults.

March 12, 2026Open Access

Accuracy of New Hypertensive Crisis Diagnoses Using International Classification of Disease (ICD)‐10: A Validation Study in a National Medicare Sample

Key Result

ICD-10 codes for hypertensive emergency and urgency demonstrated high positive predictive values of 91% and 97% respectively using physician evaluation in a Medicare sample.

Key Points

This study aims to evaluate the accuracy of ICD-10 codes for diagnosing hypertensive crises among older adults.
Analyzed a 20% national sample of fee-for-service Medicare beneficiaries aged ≥66 years (2016-2019).
Reviewed medical records for randomly sampled emergency department visits or hospitalizations with primary ICD-10 HTN crisis codes.
Used two gold standards to validate diagnoses: treating physician diagnosis and adjudicated diagnosis based on blood pressure readings.
PPV for HTN emergency (I16.1) was 91% using the treating physician gold standard.
PPV for HTN urgency (I16.0) was 97% using the treating physician gold standard.
Overall PPV for any HTN crisis (I16.X) was 95% using the adjudicated gold standard.

Structured PICO

Are ICD-10 codes for hypertensive crisis accurate compared to physician diagnosis and adjudicated clinical criteria in older Medicare beneficiaries?

Population

220 randomly sampled emergency department visits or hospitalizations with a primary ICD-10 hypertensive crisis code (from a 20% national sample of fee-for-service Medicare beneficiaries aged ≥66 years, 2016-2019). Mean age 73 years, 33% male, 66% White.

Intervention

ICD-10 codes for hypertensive crisis (I16.0 for urgency, I16.1 for emergency, I16.9 for unspecified)

Comparator

Gold standard diagnoses (treating physician diagnosis and adjudicated diagnosis based on BP criteria: SBP ≥180 mmHg or DBP ≥110 mmHg, with or without end-organ damage)

Outcome

Positive predictive value (PPV) of ICD-10 hypertensive crisis codes

ICD-10 codes for hypertensive crises demonstrate high positive predictive value, validating their use in epidemiological and health services research.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

The incidence of hypertensive (HTN) crises in older adults has more than doubled over the past two decades. ICD-10 introduced codes for HTN urgency and emergency, but their validity has not been evaluated. We analyzed a 20% national sample of fee-for-service Medicare beneficiaries aged ≥66 years (2016-2019). Medical records were reviewed for 220 randomly sampled emergency department visits or hospitalizations with a primary ICD-10 HTN crisis code (100 HTN urgency I16.0, 100 HTN emergency I16.1 and 20 unspecified I16.9). Physicians abstracted and adjudicated cases. Two gold standards (GS) were used: (1) treating physician diagnosis and (2) adjudicated diagnosis based on BP (SBP ≥180 mmHg or DBP ≥110 mmHg), with or without end-organ damage. PPVs and 95% confidence intervals were estimated. Among 220 charts sampled from 53,100 HTN crisis cases (mean age 73 years; 33% male; 66% White), PPV for HTN emergency (I16.1) was 91% (95% CI, 85%-96%) using the treating physician GS and 78% (95% CI, 71%-86%) using the adjudicated GS. PPV for HTN urgency (I16.0) was 97% (95% CI, 93%-99%) and 81% (95% CI, 72%-88%), respectively. Overall PPV for any HTN crisis (I16.X) using the adjudicated GS was 95% (95% CI, 91%-97%). Including unspecified codes reduced PPV to 86% (95% CI, 79%-92%) and 78% (95% CI, 71-86%). ICD-10 HTN crisis codes demonstrate high PPV, supporting their use in epidemiologic and health services research.