A simple single-item rating scale to measure medication adherence: further evidence for convergent validity.
BACKGROUND
Self-report measures of medication adherence are inexpensive and minimally intrusive. However, the validity of self-reported adherence is compromised by recall errors for missed doses and socially desirable responding.


METHODS
Examined the convergent validity of 2 self-report adherence measures administered by computerized interview: (a) recall of missed doses and (b) a single-item visual analogue rating scale (VAS). Adherence was also monitored using unannounced phone-based pill counts that served as an objective benchmark.


RESULTS
The VAS obtained adherence estimates that paralleled unannounced pill counts (UPCs). In contrast, self-reported recall (SR-recall) of missed medications consistently overestimated adherence. Correlations with participant characteristics also suggested that the computer-administered VAS was less influenced by response biases than SR-recall of missed medication doses.


CONCLUSIONS
A single-item VAS offers an inexpensive and valid method of assessing medication adherence that may be useful in clinical as well as research settings.
Kalichman
Seth C
SC
Department of Psychology, University of Connecticut, Storrs, Connecticut 06269, USA. seth.k@uconn.edu
Amaral
Christina M
CM
Swetzes
Connie
C
Jones
Michelle
M
Macy
Rene
R
Kalichman
Moira O
MO
Cherry
Chauncey
C
D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use; D005260:Female; D005845:Georgia; D015658:HIV Infections / Q000188:drug therapy* / Q000208:ethnology / Q000523:psychology*; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D055118:Medication Adherence / Q000523:psychology; D008875:Middle Aged; D011581:Psychological Tests; D014584:User-Computer Interface; D019562:Viral Load; D055815:Young Adult; D016903:Drug Monitoring
D044966:Anti-Retroviral Agents