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Adherence to Antiretroviral Therapy among Patients with Human Immunodeficiency Virus: Rates and Determinants
*Corresponding author: Roland Nnaemeka Okoro, Department of Clinical Pharmacy and Pharmacy Administration, University of Maiduguri, Maiduguri, Nigeria. orlandn@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Okoro RN, Bukar AD, Mudenda S. Adherence to Antiretroviral Therapy among Patients with Human Immunodeficiency Virus: Rates and Determinants. J Compr Health. 2025;13:152-7. doi: 10.25259/JCH_10_2025
Abstract
Background:
Achieving optimal adherence to antiretroviral therapy (ART) is critical for viral suppression in individuals living with human immunodeficiency virus (HIV).
Objectives:
This study assessed adherence rates among individuals on ART using pharmacy refill data, identified sociodemographic and clinical factors influencing adherence, and evaluated the relationship between adherence and viral load outcomes.
Material and Methods:
A retrospective longitudinal study was conducted among participants with HIV at a secondary public healthcare facility in Maiduguri, Nigeria. Patients 18 years and older who had filled records at the HIV clinic of at least 12 months’ supplies of ART were included in the study. Sociodemographic characteristics and viral load values were extracted from medical records. Adherence was measured using the proportion of days covered method, which was determined based on ART dispensing records from January to December 2023. Chi-square test and logistic regression analyses were used to identify factors associated with adherence, while correlation analysis was performed to investigate the relationship between adherence and viral suppression. P < 0.05 was considered statistically significant.
Results:
Among 300 participants included in the study, 61.0% were female, and 53.3% were aged 30–49 years. ART good adherence rate of 97.7% was found in the study population. Adherence was significantly associated with marital status (P = 0.012) and viral load levels (P = 0.011). Married individuals (61.4%) showed better adherence compared to single participants (38.6%). Participants with viral loads of <20– 75 copies/mL were more likely to adhere, while those with >200 copies/mL demonstrated poorer adherence (adjusted odds ratio = 0.07, P = 0.035). A significant negative correlation was observed between adherence and viral load (r = −0.360, P < 0.001).
Conclusion:
This study found that an overwhelming proportion of the study participants demonstrated good ART adherence. Sociodemographic characteristics, particularly marital status, and baseline viral load levels, significantly influenced adherence. Tailored interventions targeting the identified vulnerable groups are essential to improving adherence and optimizing treatment outcomes among people living with HIV.
Keywords
Adherence
Antiretroviral therapy
Human immunodeficiency virus
Proportion of days covered
Viral load
INTRODUCTION WITH OBJECTIVES
Human immunodeficiency virus (HIV) continues to be a significant global health issue, responsible for approximately 42.3 million deaths to date.1 By the end of 2023, about 39.9 million individuals were living with the virus, with 65% residing in the World Health Organization African Region.1 In Nigeria, an estimated 2.1% of adults aged 15–49 years are living with HIV, equating to roughly 2 million individuals across the country.2 At present, there is no cure for HIV. However, with proper access to prevention, diagnosis, treatment, and care – particularly for opportunistic infections – HIV can be managed as a chronic condition. This allows individuals living with the virus to maintain long and healthy lives. Antiretroviral therapy (ART) extends life expectancy and effectively lowers viral load, helping to prevent disease progression and transmission.3,4 However, its effectiveness relies heavily on consistent adherence, typically at 90% or higher, to maintain virological suppression and reduce the risk of drug resistance.5
Adherence to ART is influenced by various factors, including sociodemographic characteristics, psychological support, access to healthcare services, and individual health literacy. Studies have demonstrated that demographic factors such as age, marital status, and education level play critical roles in shaping adherence behaviors.6-9 For instance, married individuals often benefit from enhanced social support, while adolescents young adults, and those with limited educational backgrounds may face challenges related to understanding the importance of adherence or navigating healthcare systems.
Despite the availability of effective ART, adherence remains suboptimal in many populations,9-14 resulting in poor virological outcomes and increased transmission risk.15,16 Understanding the factors associated with adherence and their impact on viral load suppression is critical for designing effective interventions tailored to diverse populations.
Most studies’ reliance on self-reported data for ART adherence might introduce bias. Participants may overestimate their adherence due to social desirability bias, leading to inflated adherence rates. Incorporating objective measures of adherence, such as pharmacy refill data, would strengthen the validity of the findings. This study sought to evaluate adherence levels among individuals on ART using pharmacy refill data, identify sociodemographic and clinical factors influencing adherence, and assess the correlation between adherence and viral load outcomes. By exploring these aspects, the study seeks to provide insights that can inform strategies to enhance adherence and improve treatment outcomes for people living with HIV in Nigeria.
MATERIAL AND METHODS
Study design and setting
This retrospective longitudinal study was conducted among individuals who received ART from January to December 2023 at State Specialist Hospital, Maiduguri, Nigeria. This hospital is a secondary-level referral facility located in the heart of the Maiduguri metropolis. The facility serves a diverse population of people living with HIV.
Sample size
The sample size was calculated with the Raosoft© online sample size calculator using 1000 as the total number of people living with HIV on first-line ART, 5% as the margin of error, and 50% response distribution to arrive at a minimum of 278 participants.
The study population
Participants were adults (≥18 years) who had been on first-line ART (Tenofovir, Lamivudine, and Dolutegravir) for a minimum of 1 year. Individuals with incomplete medical records during the study period were excluded from the study. The medical records of patients that were included in this study were systematically and randomly selected using an interval of three.
Data collection
Data were collected between September and December 2024 using predesigned pro forma containing three sections. Sections A, B, and C collected sociodemographic, clinical, and ART dispensing data, respectively. Sociodemographic information, including age, sex, marital status, religion, employment status, and educational attainment, clinical data (viral load measurements at baseline and follow-up), and ART dispensing data were retrieved from medical records.
Outcome measures
The main outcomes included good adherence, defined as 90% or higher PDC, and viral load suppression, defined as viral load <200 copies/mL. Secondary outcomes included factors associated with good adherence and changes in viral load from baseline to follow-up.
Data processing
Adherence to ART was assessed using the PDC method, based on ART dispensing records from January and December 2023. In this study, the 90% PDC threshold recommended for ARTs was used.5 The PDC threshold represents the minimum level at which medication adherence is likely to provide the majority of its intended clinical benefits. The 90% PDC threshold measure was calculated by dividing the sum of all days covered with a complete ART regimen by the duration of the study (365 days). This value was then multiplied by 100 to calculate the PDC percentage for each patient. To calculate overall adherence percentage rates in the study population, the number of patients with a PDC of 90% or higher was divided by the overall count of patients included in the study, then multiplied by 100.
Adherence to ART was categorized as either “poor” or “good” based on Pharmacy Quality Alliance (2022) criteria.5 PDC of ≥ 90% was considered good adherence. In the logistic regression analysis, adherence rates below 90% were assigned zero points, while adherence rates of 90% or higher were assigned one point.
For viral load measurements, the first viral load for the year served as the baseline, while the second (final) measurement for the year, as per hospital protocol, served as the follow-up viral load.
Statistical analysis
The extracted data from the medical records were first entered into a Microsoft Excel spreadsheet, cleaned, coded, and transferred to Statistical Products and Services Solution version 21 (IBM Corporation) for Windows software for analysis. Descriptive statistics (mean ± standard deviation, frequencies, and percentages) were used to summarize participants’ sociodemographic and clinical characteristics. A Chi-square test was employed to assess associations between categorical variables and adherence levels. Logistic regression analysis was conducted to identify predictors of good adherence, while Pearson correlation analysis examined the relationship between adherence and viral load. P < 0.05 was considered statistically significant.
RESULTS
Basic characteristics of the study population
The study included 300 participants, of which 61.0% were female and 39.0% male. The mean age of the participants was 33.3 ± 10.2 years. The age distribution showed that the majority (53.3%) were aged 30–49 years, and 8.7% were aged 50 years or older. Most participants were married (60.3%), while Islam was the predominant religion (81.0%). Regarding employment, 54.0% were unemployed, and 46.0% were employed. Educational attainment varied, with the highest proportion having secondary education (35.3%), with a smaller proportion having tertiary education (17.0%). Viral load distribution showed that 61.7% had levels between <20 and 75 copies/mL, while 14.0% had levels of >75–200 copies/mL [Table 1].
| Variables | n(%) |
|---|---|
| Sex | |
| Female | 183 (61.0) |
| Male | 117 (39.0) |
| Age group (years) | |
| 18–29 | 114 (38.0) |
| 30–49 | 160 (53.3) |
| ≥50 | 26 (8.7) |
| Marital status | |
| Single | 119 (39.7) |
| Married | 181 (60.3) |
| Religion | |
| Christianity | 57 (19.0) |
| Islam | 243 (81.0) |
| Employment status | |
| Unemployed | 16 (54.0) 2 |
| Employed | 138 (46.0) |
| Educational level | |
| None | 87 (29.0) |
| Primary | 56 (18.7) |
| Secondary | 106 (35.3) |
| Tertiary | 51 (17.0) |
| Viral load (copies/mL) | |
| <20–75 | 185 (61.7) |
| >75–200 | 42 (14.0) |
| >200 | 73 (24.3) |
Adherence rate and its associated factors
Of the 300 participants, 293 (97.7%) had good adherence. Table 2 highlights factors associated with adherence. Marital status and viral load showed statistically significant associations with adherence levels (P = 0.012 and P = 0.011, respectively). Married participants exhibited better adherence compared to single individuals. Participants with lower viral loads (<20–75 copies/mL) were more adherent compared to those with higher viral loads (>200 copies/mL).
| Variables | Adherence categories | P-value | ||
|---|---|---|---|---|
| Total n (%) | Poor n (%) | Good n (%)z | ||
| Sex | ||||
| Female | 183 (61.0) | 5 (71.4) | 178 (60.8) | 0.567 |
| Male | 117 (39.0) | 2 (28.6) | 115 (39.2) | |
| Age group (years) | ||||
| 18–29 | 114 (38.0) | 5 (71.4) | 109 (37.2) | 0.110 |
| 30–49 | 160 (53.3) | 1 (14.3) | 159 (54.3) | |
| ≥50 | 26 (8.7) | 1 (14.3) | 25 (8.5) | |
| Marital status | ||||
| Single | 119 (39.7) | 6 (85.7) | 113 (38.6) | 0.012* |
| Married | 181 (60.3) | 1 (14.3) | 180 (61.4) | |
| Religion | ||||
| Christianity | 57 (19.0) | 2 (28.6) | 55 (18.8) | 0.514 |
| Islam | 243 (81.0) | 5 (71.4) | 238 (81.2) | |
| Employment status | ||||
| Unemployed | 162 (54.0) | 6 (85.7) | 156 (53.2) | 0.088 |
| Employed | 138 (46.0) | 1 (14.3) | 137 (46.8) | |
| Educational levels | ||||
| None | 87 (29.0) | 3 (42.9) | 84 (28.7) | 0.481 |
| Primary | 56 (18.7) | 0 (0.0) | 56 (19.1) | |
| Secondary | 106 (35.3) | 2 (28.6) | 104 (35.5) | |
| Tertiary | 51 (17.0) | 2 (28.6) | 49 (16.7) | |
| Viral load (copies/mL) | ||||
| <20–75 | 200 (66.7) | 1 (14.3) | 199 (67.9) | 0.011* |
| >75–200 | 38 (12.7) | 2 (28.6) | 36 (12.3) | |
| >200 | 62 (20.7) | 4 (57.1) | 58 (19.8) | |
Predictors of good adherence
Multivariate analysis [Table 3] identified several potential predictors of good adherence. Married individuals had higher odds of adherence (adjusted odds ratio [AOR] = 9.97, P = 0.075) compared to single participants, although this was not statistically significant. Viral load remained a significant predictor; participants with viral loads of >200 copies/mL were less likely to adhere (AOR = 0.07, P = 0.035) compared to those with levels of <20–75 copies/mL.
| Variables | AOR (95% CI) | P-value |
|---|---|---|
| Sex | ||
| Female | 1.00 (Reference) | |
| Male | 5.49 (0.61–49.47) | 0.129 |
| Age group (years) | 0.335 | |
| 18–29 | 1.00 (Reference) | |
| 30–49 | 7.09 (0.37–137.60) | 0.196 |
| ≥50 | 4.86 (0.28–85.83) | 0.281 |
| Marital status | ||
| Single | 1.00 (Reference) | |
| Married | 9.97 (0.79–125.86) | 0.075 |
| Religion | ||
| Christianity | 1.00 (Reference) | |
| Islam | 1.07 (0.14–8.26) | 0.949 |
| Employment status | ||
| Unemployed | 1.00 (Reference) | |
| Employed | 3.28 (0.23–46.26) | 0.379 |
| Educational levels | 0.288 | |
| None | 1.00 (Reference) | |
| Primary | ||
| Secondary | 6.31 (0.64–62.58) | 0.116 |
| Tertiary | 0.56 (0.06–5.43) | 0.620 |
| Viral load (copies/mL) | ||
| <20–75 | 1.00 (Reference) | |
| >75–200 | 0.07 (0.00–1.07) | 0.056 |
| >200 | 0.07 (0.01–0.83) | 0.035* |
Relationship between adherence and viral loads, and the distribution of viral loads of the study participants
Pearson correlation analysis revealed a significant negative correlation between viral load and adherence (r = −0.360, P < 0.001). Figure 1 illustrates the distribution of viral loads among study participants at baseline and follow-up. At the baseline, a notable proportion of participants (24.3%, n = 73) had higher viral loads (>200 copies/mL). However, at follow-up, there was a marked shift toward lower viral loads, with a substantial increase in the number of participants (66.7%, n = 200) achieving viral suppression (<20–75 copies/mL). Despite this general improvement, 38 (12.7%) participants remained in the higher viral load categories (>75 copies/mL).
- The distribution of viral loads of study participants.
DISCUSSION
The results of the study present some compelling insights into the relationship between ART adherence and viral load among participants. With an impressive adherence rate of 97.7%, it suggests that the vast majority of our participants are successfully managing their medication regimens. This aligns with findings from a study of similar populations that filled ARTs in community pharmacies in the US, which also evaluated adherence using the PDC approach,17 suggesting that effective interventions and support systems may be playing a crucial role in achieving these outcomes.
However, the distribution of viral loads at baseline and follow-up reveals a more complex picture. While there was a decrease in the proportion of participants with viral loads of >200 copies/mL from 24.3% to 20.7%, the fact that a considerable portion still experienced higher viral loads indicates that there are underlying challenges that need to be addressed. The substantial increase in participants achieving viral suppression (66.7%) is encouraging and suggests that adherence is indeed impactful, as supported by other studies,18-20 which emphasize the direct correlation between adherence and viral load control.
Interestingly, the findings of the present study on marital status and adherence levels highlight an important social factor that influences health behaviors. Married individuals showed better adherence compared to their single counterparts, which is consistent with studies that point to the positive effects of social support on health outcomes.8,21 Although the association was not statistically significant in the multivariate analysis, it reinforces the idea that social structures can play a key role in adherence to treatment.
The inverse relationship between viral load and medication adherence highlights an important trend. Individuals who maintain lower viral loads tend to exhibit higher adherence to their prescribed treatment. This is consistent with findings from other research indicating that patients who experience better health outcomes are often more motivated to maintain their treatment regimens.22-25 The stark contrast in adherence odds of individuals with higher viral loads further emphasizes the importance of developing targeted interventions that incorporate both psychological and social factors.
Limitations
There are some limitations worth discussing. First, while the adherence rates are impressive, limiting the study to only one hospital and the lack of qualitative data to explore underlying factors warrant caution in generalizing findings. Future research should incorporate larger and more diverse participant groups to enhance the generalizability of these findings across various demographic populations. Another limitation is the relatively small percentage of participants who remained in the higher viral load categories. While it is encouraging that most improved, understanding the reasons behind the persistent higher viral loads in this subgroup could provide deeper insights into barriers to adherence. Factors such as mental health issues, or access to care could be at play, but this study did not delve into those aspects. Furthermore, while marital status showed a significant association with adherence, the odds ratio for married individuals did not reach statistical significance. This suggests that while there is a trend, the data may not be robust enough to draw firm conclusions. Larger studies could help clarify this relationship further.
CONCLUSION
While the study demonstrates high adherence rates and an overall improvement in viral suppression, the persistence of higher viral loads in some participants signals that ongoing efforts are needed to address barriers to adherence. Good adherence was closely linked to lower viral loads, emphasizing the need for sustained efforts to support adherence among people living with HIV. Sociodemographic factors, particularly marital status and baseline viral load levels, emerged as significant influencers of adherence behaviors. These insights point to the necessity for tailored interventions, including enhanced social support systems, patient education, and targeted adherence strategies, to address the barriers faced by individuals, particularly those who are single or experiencing higher viral loads, to enhance their treatment outcomes.
Ethical approval:
The research/study was approved by the Institutional Review Board at State Specialist Hospital, Maiduguri, Nigeria, number SSH/GEN/641/Vol 1, dated 8th August 2024.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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