Noncommunicable disease burden among HIV patients in care: a national retrospective longitudinal analysis of HIV-treatment outcomes in Kenya, 2003-2013

The last decade has witnessed an unprecedented growth in coverage of HIV care and treatment programs globally. Expanded criteria for initiation of highly effective antiretroviral therapy (ART) for people living with HIV (PLHIV) has been associated with increased longevity and favorable treatment outcomes [1, 2]. Over the same period, noncommunicable diseases (NCDs) and associated deaths have risen steadily. At a global scale, the World Health Organization (WHO) estimates 41 million NCD-related deaths occur on an annual basis [3]. Three quarters of these deaths are in low and middle-income countries. In the general population, four major NCDs - cardiovascular diseases (including hypertension, heart attack and stroke), cancer, chronic respiratory diseases and diabetes mellitus make the largest contribution to both morbidity and mortality [4].

Sub-Saharan Africa (SSA), which is home to over half of the estimated PLHIV worldwide, is faced with a dual disease epidemic – communicable diseases and NCDs [5‐7]. While several countries in SSA continue to report rapid scale-up of their national ART programs [1, 7, 8], a concomitant rise in incidence of NCDs and NCD-related deaths has also been observed over the last decade [9]. NCDs, and particularly the four aforementioned, account for over half of all hospital admissions and deaths in Kenya [6, 10]. Increased longevity of PLHIV on ART suggests likely increases in prevalence of NCDs among PLHIV in the future [1, 7, 8, 11, 12].

The burden and impact of NCDs among PLHIV in lower and middle income countries with robust ART programs is still not clearly defined [13]. Several studies examining NCDs among PLHIV have been conducted in SSA [14‐18]. Most of these have involved cross-sectional surveys of facility level data, with smaller and less-representative samples. Previous national HIV treatment outcome studies in SSA have also not addressed NCDs among PLHIV [8, 19]. Additionally, there is paucity of data on the impact of noncommunicable disease burden among PLHIV from early public health approaches in HIV programming that stratified clients in care based on declining CD4 counts [20]. PLHIV in care with low CD4 counts as per prevailing national guidelines were considered eligible for HIV treatment and had ART included in their care; accordingly these “ART cohorts” were different from the corresponding clients in “pre-ART cohorts” who had higher CD4 counts than the then established thresholds for ART initiation.

Using a nationally representative sample, we sought to estimate the burden of NCDs among PLHIV enrolled in HIV care and treatment in Kenya between 2003 and 2013.

This evaluation describes the burden of NCDs among HIV patients from a nationally representative survey of HIV care and treatment in Kenya prior to the national implementation of ART for all PLHIV irrespective of CD4 count. This evaluation was conducted in the context of a rising burden of NCDs in Africa and a rapid scale up of antiretroviral therapy coverage that has contributed to increased life expectancy among PLHIV [2, 14, 25‐27]. In this study overall incidence rates for diagnosed NCDs were lower amongst those on ART compared to those not on ART. It is possible that this can be attributed to differences in health seeking behaviors, health care access, or socioeconomic or other factors associated with delayed initiation of ART. This finding is consistent with other studies that have shown increased prevalence of NCD risk factors among PLHIV not on antiretroviral treatment [28, 29]. Compared to other studies that suggest social economic deprivation as a predictor of NCDs risk factors among PLHIV [18, 30], our study did not detect a difference based on employment status.

The WHO’s recommendation to expand ART eligibility to all persons diagnosed with HIV was adopted in Kenya in 2016 [31]. Clinical parameters of WHO stage and baseline CD4 have previously been associated with NCD risk [32]. In our study, WHO staging and baseline CD4 showed no significant associations with NCDs risk, although documentation was incomplete.

In other countries, an increased risk of developing NCDs in PLHIV has been associated with exposure to certain ART drugs like stavudine, efavirenz and protease inhibitors [33‐36]. A meta-analysis showed that exposure to ART drugs independently increases risk of metabolic and cardiovascular diseases [37]. However, our study and a study conducted in Zimbabwe conducted found no significant association between either ART drug class or duration of exposure and NCDs [14]. This discrepancy may result from limitations in detecting NCDs in our study, specific ARTs in use during this study period, or differences between populations.

The convergence of a dual burden of NCDs and communicable diseases in SSA is not in question [2, 6, 17, 27]. The burden of hypertension and cardiovascular disease regardless of HIV status remains substantial [38, 39]. Several studies have shown evidence of increased blood pressure and hypertension among PLHIVs on ART; an indication that a distinct difference exists in the characterization of cardiovascular disease between PLHIVs and non-PLHIVs [37, 40].

By using two elevated blood pressure readings within a 12 month interval (as a proxy for hypertension), our study found elevated blood pressure to be the most common (87.5%) among the 4 selected NCDs in our study population. In comparison, only 0.5% of these patients had a recorded diagnosis of hypertension. This discrepancy highlights the need for systematic screening NCDs in this population. The population of PLHIV in care that had been diagnosed with diabetes mellitus was comparable to that of the general population with raised blood glucose (2.1% vs 1%) [10]. Our study findings are similar to those of several studies and population based NCDs surveys in SSA [10, 15, 38]. There is a need to emphasize cardiovascular and metabolic risk factor assessment at all clinical visits, especially for PLHIV in older age groups [6, 13, 17, 41].

Our study found a lower prevalence of chronic respiratory diseases, including asthma, among PLHIV enrolled in care when compared to estimates for the general population derived from a separate national survey of NCDs (2.3% vs 8.5%) [10]. Although noted to be a lower prevalence, deliberate screening for findings and risk factors associated with chronic respiratory conditions such as smoking and occupational hazards should be incorporated in routine screening [42]. Of note, most facilities did not perform spirometry for respiratory disease evaluation.

Cancers are the second largest cause of NCD-related deaths and account for 7% of overall mortality in Kenya [6]. In our study, the prevalence of cancer among PLHIV enrolled in care was 1.1%. In an era of increased access to ART, systematic reviews among PLHIV indicate steadily declining rates of AIDS defining malignancies among PLHIV with most cancer diagnoses now being pre-cancerous [40]. Screening of cancers, such as cervical cancer, however remains important and cost-effective when integrated into HIV care and treatment [31, 43].

The study data were abstracted from HIV care facility clinical records. The absence of standard processes, guidelines, and diagnostic tools for screening and testing for NCDs at HIV care facilities resulted in our survey underestimating NCD burden. Data for all NCD categories, except for elevated blood pressure, were identified through documentation of diagnoses in clinic records. Notably, the majority of patients who were classified as having an NCD in this survey were identified through review of serial blood pressure measurements, and not through a documented history of hypertension in the medical record. Additionally, patients with conditions associated with high mortality such as stroke, myocardial infarction, and severe heart failure may be less likely to be identified through clinic records, either not reaching initial care or being lost-follow-up prior to diagnosis. The high proportion of patients lost to follow up in this cohort likely also resulted in an underestimated of NCD burden. The retrospective design of our study limited our analysis of risk factors for NCDs among PLHIV that would have bolstered our study findings and allowed us to make robust comparisons to other nationwide NCD surveys [44].

We identified a high prevalence of NCDs among PLHIVs in Kenya that likely represents a substantial underdiagnoses of these categories of NCDs. Systematic screening and treatment for NCDs using standard guidelines should be integrated into HIV care and treatment programs in sub-Saharan Africa [2, 27]. Knowledge of NCDs burden could be improved through surveillance mechanisms and registries [45]. As Kenya seeks to reach the ambitious UNAIDS 90–90-90 goals through expanded treatment, strategies need to be developed that ensure health gains for PLHIVs are not eroded by a rising burden of NCD morbidity and mortality.