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Single Coverage for MAM programmes

This question was posted the Coverage assessment forum area and has 1 replies.

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Ben Allen

Normal user

5 Jul 2019, 12:02

Dear community,

Does anybody know about using single coverage for MAM?

I guess length of an untreated case and duration of stay would need to be appropriate for MAM. We can know duration of stay from routine data. But how can we know length of untreated case? Since the SAM one comes from historical data, I'd be surpirsed if it exisits for MAM.

Or maybe in the absence of this information it’s advisable to use the imperfect point estimator.

Any suggestions would be very helpful as I support a programme to estimate MAM coverage in a camp alongside SAM coverage.

Many thanks in advance


Mark Myatt

Frequent user

5 Jul 2019, 14:49

It is not, I think, a good idea to pick one or the other (i.e. point or period coverage). The best choice will depend on context ...

If the program has good case-finding and recruitment, short lengths of stay, and low levels of defaulting then the period coverage estimator is likely to be the most appropriate estimator.

If the program has poor case-finding and recruitment, long lengths of stay due to late presentation and / or late admission, and high levels of defaulting then the point coverage estimator is likely to be the most appropriate estimator.

Point and period estimators measure different things ...

Point coverage reflects the ability of a program to find and recruit cases. The point coverage estimator does not account for recovering cases and so does not directly reflect the program's ability to retain cases from admission to cure. This means that it may give a misleading (i.e. downwardly biased) picture of program performance. This is a particular problem with programs that recruit cases very soon after they meet program admission criteria and are likely to be treating large numbers of recovering cases. In these programs the point coverage estimator will “penalise” good performance.

Period coverage is intended to reflect the ability of a program to find, recruit, and retain cases. The period coverage estimator does directly reflect the program's ability to retain cases from admission to cure but tends to overestimate program performance because the denominator does not include recovering cases that are not in the program. The period coverage estimator also overestimates program performance when cases are retained in a program after meeting the criteria for being discharged as cured.

The single coverage estimator is an attempt to correct these biases while maintaining compatibility with existing methods and allowing historical comparisons to be made. It relies on some estimate of the ratio of the mean length of an untreated episode to the mean length of a treated episode.

For SAM we have relied on published estimates but methods for estimating caseloads have been developed in recent years that allow us to estimate the  mean length of an untreated episode. We can use both approaches for MAM.

SURPRISE!!! Here are some published estimates of the duration of an untreated MAM episode.

I hope this is of some use.

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