Could caregiver reporting adherence help detect virological failure in Cameroonian early treated HIV-infected infants?

PEDIACAM is a prospective cohort study of HIV-infected infants included between November 2007 and October 2011 in three referral hospitals in Cameroon: the Centre Mère et Enfant de la Fondation Chantal Biya (CME/FCB) and Centre Hospitalier d’Essos (CHE) both in Yaounde and Hôpital Laquintinie de Douala (HLD) in Douala. The inclusions in PEDIACAM were organized in two phases and are described elsewhere [18]. In brief, during the first phase, infants born to HIV-infected mothers and those born to HIV-uninfected mothers were matched according to gender and site of recruitment during the first week of life and followed until the fourteenth week. During the follow-up period, all infants received routine vaccines according to the Expanded Program of Immunization, planned at 6, 10 and 14 weeks. HIV-exposed infants underwent HIV molecular diagnostic tests (HIV-DNA PCR or HIV-RNA PCR) at 6 weeks of age and the results were available at week 10. HIV-positive infants were confirmed by testing a second sample collected at age 10 weeks. Breastfed infants with previously negative HIV tests were retested 6 weeks after weaning. All HIV-infected infants and subsamples of uninfected HIV-exposed infants and HIV-negative unexposed infants were eligible for the second phase of follow-up planned to continue to age 2 years. Inclusion into phase 2 was also offered directly to HIV-infected infants not followed from the first week of life but diagnosed before the age of 7 months.

Overall, 210 HIV-infected infants were included in the second phase: cART was proposed systematically to these children as soon as the HIV status was confirmed. The initial cART regimen depended on PMTCT (Prevention of Mother-to-Child Transmission) history and followed the Cameroonian guidelines at the time of the study which recommended zidovudine (or abacavir or stavudine if anemic), lamivudine and lopinavir/r if there was any use of nevirapine for PMTCT (or nevirapine otherwise). The caregivers were asked to administer the drugs to the infants twice daily (every 12 h). A standardized questionnaire was administered every 3 months after initiation of cART by a health care provider (physician, nurse, psychosocial worker or pharmacist) to assess infant adherence to cART during the period and to identify and help families with any difficulties. In total, eight questionnaires were planned from month 3 (M3) to month 24 (M24) of follow-up. The HIV viral load was measured at the same follow-up time points using RT PCR (Biocentric, Bandol, France).

The adherence questionnaire was similar to the questionnaire used in the PENTA trial, with some adaptations [16]. It included questions about: the relationship between the caregiver and the child; difficulties experienced during drug administration; the most difficult dose to remember; how administration of cART interfered with everyday life; reasons for the difficulties identified; and the caregiver’s recall of missed doses in the past 3 and 14 days.

Among the 210 HIV-infected infants included in phase 2 of the PEDIACAM study, 13 died before treatment started and five refused cART. For the 192 infants who initiated cART, 25 died during the first three months of treatment. Thus, 167 HIV-infected infants treated for at least three months were included in this analysis (Fig. 1). Infants without virological data at a particular time point (because of death or missing values) were not included in the analysis at that particular time point. There were: 33 (19.8 %) such children at M3, 9 (5.4 %) at M12 and 6 (3.6 %) at M24.

The quarterly monitoring values used were the nearest measurement within a ±1.5 month interval of each of the following times after cART initiation: M3, M6, M9, M12, M15, M18, M21 and M24.

The main outcome was virological failure at M3, M12 and M24, defined as viral load higher than 1000 copies/mL (at M3 or M12) or higher than 400 copies/mL (at M24). We chose a higher threshold for M3 and M12 because a previous African study of HIV-infected infants under 12 months of age reported very high viral loads at baseline and that treatment duration contributed to lower viral loads at M24 [19]. HIV resistance genotyping by sequence amplification and interpretation according to the French ANRS interpretation algorithms was carried out for selected cases of virological failure associated with reporting suggesting adequate adherence.

The outcome measures also included non-adherence at the various time points recorded as: “current missed doses” (criterion A) defined as the number of cART doses not administered to an infant at a particular time point (M3, M12 or M24) and “cumulative missed doses” (criterion B) which was the sum of cART doses reported as not administered every three months during the corresponding interval M3 to M12 or M3 to M24. We also used mixed criteria (A or B, A and B). When a quarterly visit was lacking, all the cART doses for this visit were considered to be missing. When a quarterly visit was performed but the adherence questionnaire not completed, we considered the previous number of missed doses for that particular visit.

Many different thresholds (5, 10, 15 and 20 %) for current missed doses have been used in previous studies in the literature to define non-adherent HIV-infected patients [13, 14, 16, 19‐21]. We compared many of these thresholds, using receiver operating characteristic (ROC) curves, maximizing the sensitivity, to determine cutoff points for missed dose values that are optimal for detecting virological failure at the various time points (viral load ≥1000 copies/mL at M3 and M12, or ≥400 copies/mL at M24). Infants with values above this cut-off were defined as non-adherent. We performed area under the curve (AUC) tests for criteria A and B for M3, M12 and M24. We estimated the sensitivity (proportion identified as non-adherent among children with virological failure) and specificity (proportion identified as adherent among those with virological success) of the approach. We also estimated positive predictive value (PPV; probability of virological failure among children whose caregiver reported non adherence) and negative predictive value (NPV; probability of virological success among children whose caregiver reported adherence). We then estimated positive and negative likelihood ratios (LR): the ratio of probability to be “non-adherent” (LR+) or to be “adherent” (LR−) for a child with virological failure versus virological success.

We studied associations between missed dose A or B criteria and various other items in the adherence questionnaire: problems with giving medication (difficulties during drug administration, the most difficult dose to remember, how administration of cART interferes with everyday life, reasons for the difficulties), type of caregiver and health care provider, the time point of the visit. Univariate analysis was first performed, using Chi square or Fisher’s exact test, as appropriate. Adjusted odds ratios (aOR) were estimated in multivariate logistic regression models, with reported missed dose as the dependent variable. For all analyses, p-values less than 0.05 (two-sided) were considered statistically significant. All the statistical analyses were performed using STATA 12.0 (StataCorp, College Station, TX).

The ANRS-PEDIACAM study was granted ethical approval in Cameroon by the National Ethics Committee and in France by the Biomedical Research Committee of the Pasteur Institute of Paris. The Cameroon Ministry of Public Health gave administrative authorization to start the study. Caregivers signed written informed consent for participating in the study.

Among the 167 HIV-infected children included (Fig. 1) in this analysis, 45.5 % were boys. Half of the infants were living with both of the parents, 38 % with their mothers only and 12 % with other caregivers; 6.6 % were motherless orphans (Table 1). cART was initiated at median age of 4 months (IQR: 3–9), when the median viral load (VL) was 6.5 log10 copies/mL (IQR: 6.0–6.9) and median CD4 percentage 22 % (IQR: 15–31 %). Respectively 34 and 64 % of infants started cART with nevirapine-based and lopinavir-based regimens. Three quarters of the infants were enrolled in Yaounde. Two years after cART initiation, 92.2 % (154/167) of infants were alive, and 144 attended the M24 visit. Thirteen infants died, including nine before M12, and four between M12 and M24 (Table 2).

Adherence questionnaires were administered by physicians (34.8 %), pharmacists (31.5 %), psychosocial workers (19.8 %) and nurses (13.9 %), and the respondent was mostly the mother (in 79.0 % of cases at M3, 73.1 % at M12 and 71.6 % at M24). According to respondents, cART medication was usually administered by the mother (84.3 % at M3, 81.1 % at M12 and 77.9 % at M24) although other caregivers may also have been involved in cART administration (63.8, 70.2 and 73.8 %, respectively).

For current missed doses (criterion A), the cutoff point which provided the best compromise between sensitivity and specificity, according ROC curves, was ≥1 missed dose at all visits (Table 3). For cumulative missed doses (criterion B), the best cutoff points were ≥2 missed doses at M12 and ≥8 missed doses at M24. With these cutoff points, the proportions of non-adherent children according to reported current missed dose were 27.4 % (40/146) at M3, 11.1 % (14/126) at M12 and 13.9 % (11/79) at M24. The proportions, based on the cutoff values for cumulative missed doses, were 23.8 % (30/126) at M12 and 62.0 % (49/79) at M24.

The area under the curve (AUC) was not significantly different to 0.5 for any missed dose criterion, except for cumulative missed doses at M12 (p = 0.005 for VL ≥ 1000 cp/mL) (Table 3 and Fig. 2).

The proportions of infants with virological failure (defined as >1000 copies/mL) 3 and 12 months after cART initiation were respectively: 47.8 % (61/146) and 23.8 %. Twenty-four months after cART initiation, the proportion of virological failure (defined as >400 copies/mL) was 27.9 % (22/79) (Table 2).

The best sensitivity was observed with the cumulative missed doses criterion as reported at M12 (63.3 %) and M24 (72.7 %). But its specificity decreased with time (to 67.7 % and 42.1 %, respectively). For all criteria used, the PPV was low (≤50 %) and NPV was high (≥75 %) at both M12 and M24. Cumulative missed doses at M12 gave the best likelihood ratios (LR + =2.0 and LR− = 0.5) (Table 3). The mixed criterion for non-adherence did not perform better at detecting virological failure.

Similar results were obtained when the analysis was restricted to the more than 70 % of the children accompanied by their mothers (Table 3).

According to both current and cumulative missed dose criteria, 11 children at M12 and 3 at M24 were classified as adherent although viral load testing indicated virological failure: they were tested for genotypic antiretroviral resistance and resistance to the currently used cART was detected in seven cases. All viruses were non-B subtypes. The most prevalent mutations in the Protease gene were I13V, K20I, M36I, H69K and L89M, and the mutations in the Reverse Transcriptase gene were T215S, M184V and Y181C.

Thirteen children identified as virological successes at M12 (VL < 1000 cp/mL) and 20 children as virological successes at M24 (VL < 400 cp/mL) were classified as non-adherent according to cumulative missed dose criteria but adherent according to current missed dose criteria.

Missed dose reporting was not significantly associated with health care provider, visit time point or caregiver.