Bulletin of the World Health Organization

Electronic monitoring of treatment adherence and validation of alternative adherence measures in tuberculosis patients: a pilot study

Jossy van den Boogaard, Ramsey A Lyimo, Martin J Boeree, Gibson S Kibiki & Rob E Aarnoutse

Volume 89, Number 9, September 2011, 632-639

Table 3. Sensitivity, specificity, positive and negative predictive values, and accuracy of individual treatment adherence measures, alone and in combination, in a study of adherence to tuberculosis treatment, United Republic of Tanzania, 2010

Adherence measure Sensitivitya
Specificityb
PPVc
NPVd
Accuracye
MEMS cut-offf
MEMS cut-offf
MEMS cut-offf
MEMS cut-offf
MEMS cut-offf
< 100% < 95% < 100% < 95% < 100% < 95% < 100% < 95% < 100% < 95%
INH urine test 33 43 40 60 60 20 18 82 35 57
Urine colour test 74 86 20 27 71 21 22 89 59 38
ACTG questionnaire 70 100 30 37 27 27 73 100 60 49
BMQ 54 57 70 55 82 24 37 84 58 56
Morisky scale 15 14 100 90 100 25 30 82 38 76
Pill counts 33 29 60 63 69 15 25 79 41 57
Refill visits 22 14 100 83 100 17 32 81 43 70
Refill visits + pill counts 41 29 60 57 73 13 27 77 46 51
Refill visits + pill counts + ACTG questionnaire 79 100 0 20 68 23 0 100 57 35
Refill visits + pill counts + urine colour test 78 86 20 23 72 21 25 88 62 35
Refill visits + pill counts + BMQ 69 71 50 38 78 22 39 85 64 44
Refill visits + pill counts + INH urine test 63 71 30 37 71 21 23 85 54 43
Refill visits + pill counts + Morisky scale 41 29 60 57 73 13 27 77 46 51

ACTG, AIDS Clinical Trials Group; BMQ, Brief Medication Questionnaire; INH, isoniazid; MEMS, Medication Event Monitoring System; NPV, negative predictive value; PPV, positive predictive value.

a Sensitivity: the proportion of non-adherent individuals correctly identified as non-adherent by the measure.

b Specificity: the proportion of adherent individuals correctly identified as adherent by the measure.

c Positive predictive value: the proportion of non-adherent individuals according to the measure who were non-adherent according to MEMS.

d Negative predictive value: the proportion of adherent individuals according to the measure who were adherent according to MEMS.

e Accuracy: the proportion of individuals correctly identified as either adherent or non-adherent by the measure.

f Non-adherence defined as an adherence rate of < 100% (27 patients) or < 95% (7 patients) as assessed by MEMS.