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4CPS-237 Measuring adherence to antiretroviral treatment: correlation and concordance between two indirect methods
  1. Á López-García1,
  2. N Herranz-Muñoz1,
  3. I Salvador-Llana2,
  4. P Sanmartín-Fenollera2,
  5. M Vélez-Díaz-Pallarés3,
  6. JA Peña-Pedrosa4,
  7. C Martínez-Nieto5,
  8. A Onteniente-González1,
  9. LM Bedoya-Del-Olmo6,
  10. I Iglesias-Peinado6,
  11. J Sánchez-Rubio-Ferrández1
  1. 1Hospital Universitario de Getafe, Pharmacy Department, Getafe, Spain
  2. 2Hospital Universitario Fundación Alcorcón, Pharmacy Department, Alcorcón, Spain
  3. 3Hospital Universitario Ramón y Cajal, Pharmacy Department, Madrid, Spain
  4. 4Hospital Clínico San Carlos, Pharmacy Department, Madrid, Spain
  5. 5Hospital Universitario de La Princesa, Pharmacy Department, Madrid, Spain
  6. 6Universidad Complutense de Madrid, Facultad de Farmacia, Madrid, Spain


Background and importance Adherence is one of the most important variables for achieving the benefits of antiretroviral treatment (ART) since effectiveness and safety of current treatments are optimal.

Adherence can be measured by direct methods, which consist of measuring the substances in biological samples, or by indirect methods based on patient interviews and dispensing records.

Indirect methods have the advantages of simplicity, an easier application in daily clinical practice and lower costs.

Aim and objectives The objectives of this study were to describe ART adherence in people living with human inmunodeficency virus (HIV) and to analyse the correlation and the concordance between two indirect methods used to measure adherence: a simple single item rating scale answered with a visual analogue scale (SIRS-VAS) and the medication possession rate (MPR).

Material and methods Multicentre (5 centres), observational, prospective and cross-sectional study. We enrolled adult people living with HIV (PLHIV) on ART.

The adherence was measured using two indirect methods. One was a SIRS-VAS about the percentage of ART taken in the previous month. The other method was the MPR, calculated over the previous 6 months from dispensing records.

MPR (%) = (days covered with dispensed medication/time interval)*100.

For studing the adherence as a qualitative variable, different cut-off points were established on the SIRS-VAS and the MPR (95%, 90%, 85% and 80%), classifying participants as ‘adherent’ or ‘non-adherent’.

Spearman correlation coefficient (r) was studied between quantitative variables. Cohen’s kappa concordance coefficient (κ) was studied between qualitative variables.

P values under 5% were considered statistically significant.

Results We enrolled 128 participants, aged 20–81 years (&xbar;=46.9±11.7); 112 men, 14 women, and 2 non-binary people.

The mean±SD MPR was 96.8±7.0%. The mean±SD SIRS-VAS score was 96.9±5.8%. There was a modest correlation between both measures (r= 0.31, p<0.001).

We observed the following qualitative concordance results between both measures:

Conclusion and relevance According to the results of both the SIRS-VAS and the MPR the adherence to ART in our population is optimal. The correlation between the SIRS-VAS and the MPR was only modest. The concordance between both measures was higher for people with high adherence results.

Conflict of interest No conflict of interest

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