As defined by the National Quality Forum, measure specifications are the technical instructions for how to build and calculate a healthcare performance measure. At a minimum, measure specifications identify the “who, what, where, when, and how” of the measure. Some of the components included in most measure specifications include the target population, numerator, exclusions, exceptions, source(s) of data, type of provider(s) assessed, setting of care, and calculation algorithm. Specifications for more complex measures also may include a sampling methodology, risk-adjustment methodology, stratification scheme, scoring instructions, and/or attribution rules, and possibly, other components. Regardless of the complexity of a measure, its specifications should be complete, precise, and unambiguous, so that those collecting data and calculating the  measure can do so in a consistent (i.e., repeatable or reliable) way.

Take QPP measure #236 as an example: This measure (entitled “Controlling High Blood Pressure”) assesses the percentage of hypertensive patients whose blood pressure (BP) was adequately controlled. Although this is a relatively simple measure, the specifications are quite extensive. Note the following:

The target population reflects, broadly, those who should be included in the measure: for this measure, patients ages 18-85 with hypertension. A closer look at the specifications provides additional detail on how to identify these patients (e.g., using age at date of encounter, the CPT codes that define an eligible encounter, and the ICD-10 code that defines a diagnosis of hypertension).

The denominator used in the measure reflects a more nuanced definition of those who should be included in the measure. It takes those patients in the target population and subtracts those listed as denominator exclusions (those on hospice, those with ESRD, etc., along with the specific codes that identify these excluded patients). The assumption is there are clinical and/or practical reasons why it is not useful or reasonable to hold providers accountable for the BP of these patients, and thus they are excluded from the measure.

The numerator of the measure indicates what is being measured. It includes those patients in the denominator whose blood pressure (BP) was under adequate control, defined for this measure as having a systolic BP < 140mmHg and a diastolic BP < 90 mmHg. Note that these thresholds should be evidence-based.

Other instructions included in these specifications tell the user how to handle various scenarios that might occur (e.g., which BP to use if there are multiple BPs listed or if no BP is listed, which telehealth visits can be counted). Finally, the specifications explain “the math” used to calculate the measure results once the patients in the numerator and denominator are identified.

Not every measure will include all the components noted above (e.g., measure #236 is not risk-adjusted and is not collected via sample, so these components are not needed). Regardless, measure specifications should be expansive enough, and precise enough, so that different users know exactly how to calculate the measure. This is the first step in ensuring correct interpretation and legitimate comparison of measure results.