Understanding Health Indicators

An indicator is a defined measure of a health service, event, or population. “Patients” is not yet an indicator. “Number of outpatient visits recorded at Umuchu Ward PHC in March” is closer, because the service, the place, and the period are named.

The anatomy of an indicator

• Numerator: the events or people being counted, such as children who received pentavalent 3.
• Denominator: the group against which that count is compared, such as children who received pentavalent 1, or the estimated number of children due.
• Multiplier: usually 100 so the result can be read as a percentage, or 1,000 when the event is rare.
• Definition: who is included, who is excluded, and which document is the source.

If any of those four is missing, two officers can calculate two different percentages from the same clinic and both can look official.

Counts, proportions, rates, and ratios

Worked example: pentavalent-3 dropout

Dropout here means children recorded as starting pentavalent who are not recorded as receiving the third dose. Use the immunisation register for both numbers, for the same cohort as far as the register allows.

Pentavalent 1 = 50. Pentavalent 3 = 35. Dropout = (50 − 35) ÷ 50 × 100 = 30%.

This does not prove that 15 children received no further vaccine anywhere. Some may have continued at another facility. It does say that this facility's register cannot show a third dose for 15 of the 50 children who started.

Worked example: fourth antenatal visit

A facility records 24 fourth antenatal visits and 40 first antenatal visits in the same month. Using first visits as the denominator, 24 ÷ 40 × 100 = 60%.

Say the definition out loud before you report it: “Fourth visits as a percentage of first visits recorded this month.” That is not the same as coverage of all pregnancies expected in the ward. The expected-pregnancy denominator may come from a population estimate. If that estimate is old or was meant for a different ward, the coverage figure will look precise and still be wrong.

Denominator pitfalls in a primary healthcare centre

• Using last year's population because this year's estimate has not arrived.
• Mixing doses given with children immunised.
• Using antenatal first visits as if they were expected pregnancies, without saying so.
• Including outreach from another ward in this ward's denominator, or the reverse.
• Leaving the denominator blank and still reporting a percentage.