Hypertension Prevalence Estimator Tool

Glossary

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Obesity

Having a body mass index (BMI)—calculated as weight in kilograms over height in meters squared (kg/m2)—of 30 kg/m2 or greater when last recorded at a clinic visit. BMI can also be calculated using the following equation if weight and height data were collected in pounds and inches: weight (pounds) / [height (inches)]2 x 703

Diabetes

Determined by health care documentation, applying clinical diagnostic criteria, and/or querying administrative claims data (e.g., diabetes defined using an ICD-9-CM code of 250, ICD-10-CM codes of E10 or E11, and/or prescriptions for insulin or oral antidiabetic medications); look-back period may differ based on health system. Ideally, the health system uses the American Diabetes Association's current clinical definition for diagnosing diabetes.

Chronic Kidney Disease

Determined by health care documentation, applying clinical diagnostic criteria, and/or querying administrative claims data (e.g., CKD defined using ICD-9-CM codes of 403, 404, and 585 or ICD-10-CM codes of I12, I13, and N18); look-back period may differ based on health system. The definition used in development of this tool included: 1) having an estimated glomerular filtration rate of <60 ml/min per 1.73 m2 using the Chronic Kidney Disease Epidemiology Collaboration equation or 2) the presence of albuminuria (albumin-to-creatinine ratio of ≥30 mg/g).

Health systems with a high prevalence of patients with low socioeconomic status

Some health systems work primarily (>50%) with patients who have low socioeconomic status (e.g., have Medicaid or no health insurance, are in poverty). These patients are often at increased risk for having hypertension and related comorbidities compared to the general population. For these types of health systems, the Estimator Tool uses National Health and Nutrition Examination Survey data specific to the US population with low socioeconomic status. These data are then applied to the specific characteristics of the health systems’ patient population to determine their expected hypertension prevalence.

95% Confidence Intervals

The 95% confidence intervals (CIs) are based on how well the tool is able to leverage the National Health and Nutrition Examination Survey data, which is representative of the US population, to estimate the hypertension prevalence of the health system’s population based on that population’s characteristics. Therefore, the size of the CIs is driven mostly by sample size (i.e., the number of people seen within the health system) and not as much by the type or granularity of the data provided.

Measured hypertension prevalence

A health system’s measured hypertension prevalence is the percentage of their patient population they report having hypertension according to medical record documentation and administrative data collected for their patients. Ideally, health systems use the two or more elevated blood pressure measures at two or more outpatient office visits criteria to diagnosis hypertension among their patients. The model supporting this tool uses the blood pressure thresholds (i.e., systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg) to diagnose hypertension recommended for the general population by the Seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7). Health systems are asked to use only outpatient medical records to identify their hypertensive population and to exclude pregnant women to avoid the effect of gestational hypertension on prevalence calculations. There are likely multiple ways health systems can identify their hypertensive population, including use of administrative claims documentation (e.g., ICD-9-CM/ICD-10-CM codes for essential hypertension (401/I10), hypertensive heart and/or chronic kidney disease (402–404/I11-I13), and/or secondary hypertension (405/I15)) and/or information provided on patient problem lists. Ideally, if administrative claims data are being used, a hypertensive patient would be identified using ICD-9-CM codes 401–404 or ICD-10-CM codes I10-I13 and exclude secondary hypertension cases. If the health system reports on the National Committee on Quality Assurance’s Healthcare Effectiveness Data and Information Set Controlling High Blood Pressure measure, they may only use the ICD-9-CM code 401 or ICD-10-CM code I10 to identify their hypertension patient population and possibly exclude those patients with documented end-stage renal disease (ICD-9-CM codes of: 585.5, 585.6, V42.0, or V45.1 or ICD-10-CM codes of N18.5, N18.6, Z91.15, Z94.0, or Z99.2).

ICD9

International Classification of Disease, Ninth Revision, Clinical Modification

ICD10

International Classification of Disease, Tenth Revision, Clinical Modification


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