How to investigate Adherence to Antiretroviral Treatment ... - INRUD

CHAPTER 4. SURVEY DESIGN
Sampling Facilities
Carrying out a survey of these indicators could be done in a single facility or in a sample of
facilities. A survey to examine adherence in a large programme or system of care, such as the
National AIDS Program, should include a minimum of 20 health facilities. If a system of care
includes fewer facilities, then all of them should be included in a survey to measure system
performance. A survey in a single facility only reflects the performance in that facility so it
cannot be used to represent the performance in the country (unless it is the only facility
providing treatment).
Facilities are best selected randomly within specific strata defined by key characteristics such
as geographic location, facility type, and facility management.
The sample of facilities should be as randomly chosen as is feasible, taking into account the
logistics of travel and the days the clinics are open.
The retrospective sample of patients is 100, so that it is preferable to only choose facilities
that had at least 100 patients on ARVs six months ago. However, if one wants to look at
smaller facilities, this can be done but instead of sampling, all patients’ records should be
looked at.
The data to calculate each indicator should be collected at each facility. The sample sizes
suggested are sufficient for a moderately reliable set of adherence measures at each facility
(such as when monitoring performance over time) and a very reliable cross-sectional or
longitudinal estimates of these measures in the system as a whole. An explanation of sample
sizes and their accuracy is included in Appendix 4.
Sampling Retrospective Patient Records
The purpose of this exercise is to give us all the adherence indicators except the self report of
the exit interview. As such it is the single most important exercise of the survey.
Retrospective data from attendance records and pharmacy records are useful because they
allow computation of indicators related to success of short-term and long-term adherence,
defaulting, and clinical outcomes. It is necessary to take a sample of 100 patients who
attended the clinic during the month seven months before. To end up with information on 100
patients, it is advisable to sample 120 patients from the list of those who attended during that
month as some records may be unavailable.
This means that if the data collection is taking place in June, you need the patients who
attended in November the year before. This is because you need to follow the patient for six
whole months and if the patient attended on the last day of November, then six months from
then would be the last day of May. Depending on the month of data collection, the months to
sample patient attendance from is documented in table 6.
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