title: [Instrument for measuring psychological variables and adherence to treatment behavior in persons who are seropositive for HIV (VPAD-24)].
abstract: OBJECTIVE
  To test the psychometric properties of an instrument for measuring psychological variables and adherence to treatment behaviors in persons with HIV infection or AIDS.
  
  
  METHODS
  A cross-sectional study was performed with 68 subjects who were seropositive for the human immunodeficiency virus (HIV) and who were being treated in a health facility in the city of Hermosillo (Sonora), Mexico, at the time the study was carried out. Five consecutive statistical testing procedures were applied for data analysis: the Student t test for comparison of means, for assessing the comprehensibility of the questions; an exploratory factorial analysis with varimax rotation for determining construct validity; Cronbach's alpha coefficient for determining reliability; Pearson's correlation coefficient (r) for assessing concurrent validity; and multiple linear regression for determining predictive value.
  
  
  RESULTS
  In 25 out of a total of 30 questions, the Student t test for comparison of means gave statistical significance values of P < or = 0.05, P < or = 0.005, P < or = 0.01, and P < or = 0.001. A four-factor structure was found with the factorial analysis with varimax rotation: (1) current adherence behavior and treatment; (2) underlying reasons for adherence or lack of adherence; (3) psychological well-being and social competencies; (4) past adherence behavior with values above 1 that, taken as a whole, explain 65.50% of the variance. An overall alpha coefficient of 0.852 was obtained with the test for reliability. The test for concurrent validity showed correlations between factors 1 and 2 (r = 0.615; P < or = 0.01), between factor 2 and factors 3 and 4 (r = -0.178; P < 0.05 and r = 0.265; P < 0,05, respectively), and between factor 3 and duration of infection in months (r = 0.265; P < 0.05). Finally, multiple linear regression showed that psychological factors 2 and 4, which together explain 48.6% of the variance, predicted current adherence behavior (adjusted determination coefficient [R2] = 0.486).
  
  
  CONCLUSIONS
  According to the results obtained, the instrument has optimal reliability as well as construct validity, concurrent validity, and predictive validity.
authors.affiliation: jpina@salud.gob.mx
authors.forename: Julio Alfonso
authors.initials: JA
authors.lastname: Piña López
authors.forename: Andrés Ernesto
authors.initials: AE
authors.lastname: Corrales Rascón
authors.forename: Katherine
authors.initials: K
authors.lastname: Mungaray Padilla
authors.forename: Manuel Alejandro
authors.initials: MA
authors.lastname: Valencia Vidrio
mesh_terms: D000328:Adult; D000368:Aged; D044966:Anti-Retroviral Agents / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006679:HIV Seropositivity / Q000188:drug therapy* / Q000523:psychology* / Q000821:virology; D006801:Humans; D016014:Linear Models; D008297:Male; D008800:Mexico; D008875:Middle Aged; D008960:Models, Psychological; D010349:Patient Compliance; D011594:Psychometrics; D011795:Surveys and Questionnaires; D019562:Viral Load
chemical_list: D044966:Anti-Retroviral Agents