Background
As a global pandemic, the Human Immunodeficiency Virus (HIV) infection has become a major contributor to childhood morbidity and mortality in sub-Saharan Africa. Mother-to-child transmission accounts for about 90% of pediatric HIV infections in sub-Saharan Africa [
1]. The majority of perinatally HIV-infected children in Africa present with HIV-related symptoms by six months of age; the disease progresses rapidly with up to 50% of infected children developing Acquired Immune Deficiency Syndrome (AIDS) and experiencing mortality within the first two years of life in the absence of intervention [
2]. However, the advent of the prevention of mother-to-child transmission (PMTCT) of HIV has resulted in a significant number of perinatally HIV-infected children surviving into adolescence [
3].
Symptomatic HIV infection is associated with an early and progressive reduction in weight and pubertal growth spurt, which can affect sexual maturation and result in delayed puberty [
4,
5]. Delayed growth and puberty are particularly common in chronic diseases such as HIV/AIDS, and more frequently in adolescents with malnutrition and chronic inflammation [
6]. HIV infection can contribute to both linear growth and weight-gain disturbances in early childhood which appear as early as three months of age [
7]. The growth deficits continue to be observed as these HIV-infected children grow into adolescence. Although the exact mechanisms for the growth retardation remain speculative, some authors suggest that proteolysis of insulin-like growth factor-1 binding protein-3 (IGFBP-3) may diminish the function of insulin-like growth factor-1 (IGF-1): resulting in growth retardation [
8]. Other authors had previously reported that IGF-1 levels were reduced in HIV-infected children [
9,
10]. A collaborative comparative study in Europe conducted in eleven centers across eight European countries specifically documented an average weight and height deficits of 7 kg and 7.5 cm, respectively by 10 years of age among HIV-infected children compared to their HIV-uninfected counterparts [
11].
Similarly, the mechanisms of pubertal delay in HIV-infected children are still not fully understood. However, several factors generally referred to as dysfunction of the hypothalamic-pituitary-gonadal (HPG) axis (which includes growth-hormone dysregulation, hypothyroidism, and testosterone reduction) have been implicated in the pathophysiology [
12]. These endocrine deficiencies occur as a result of direct HIV invasion, lymphocytic infiltration, and opportunistic infections. The euthyroid sick syndrome (accompanied by increased basal thyrotropin levels, free thyroxin levels, low IGF-1, and IGF BP-3 due to HIV-triggered production of pro-inflammatory cytokines) has been identified as a possible mechanism leading to delayed sexual maturation [
13].
Whereas studies demonstrating growth and pubertal delay in male and female HIV-infected children have been conducted in the developed settings of Europe and the United States [
14‐
17], similar studies in either of the sexes or both sexes have been conducted in sub-Saharan Africa as well [
18‐
22]. In southeast Nigeria, a previous study in this locality focused on the female sex alone by investigating sexual maturation in perinatally HIV-infected girls aged 8–17 years [
23]. The present study, however, aimed to determine the physical growth and sexual maturation of perinatally HIV-infected adolescent males and compare them with those of age-matched HIV-negative controls.
Methods
Study design and site
This study was designed as a hospital-based, comparative cross-sectional study conducted at the University of Nigeria Teaching Hospital (UNTH), Ituku-Ozalla in Enugu over six months (September 2019 - February 2020). It was conducted in the Pediatric HIV and Out-Patient Clinics of the hospital. A total of 262 children aged 10 to 19 years were registered in this Pediatric HIV Clinic, comprising 117 males (112 perinatally infected) and 145 females as of September 2019. The clinics attended to children up to 19 years because there was also a specialty Paediatric Adolescent Clinic which worked synergistically with other clinics during this transition phase in guiding the patients’ transition to the equivalent adult clinics.
Study population and sampling method
The study subjects were adolescent males attending HIV and Children Out-Patient Clinics. Perinatally HIV-infected males (aged 10–19 years) on highly-active anti-retroviral therapy (HAART) were included as the study subjects. The controls were healthy HIV-negative males (aged 10–19 years) who had no acute illness for at least 2 weeks before recruitment. They were patients on follow-up visits after recovery from curable infectious diseases (such as malaria and acute respiratory infections). They had pre-test and post-test HIV counseling sessions which were conducted routinely by a trained dedicated counselor from the HIV Clinic working synergistically with the Children Out-patient Clinic for on-site counseling and testing. Additionally, these controls were investigated for HIV in two sequential screening tests. Participants excluded from the study consisted of the following: HIV-infected males (aged 10–19 years) on long-term medications that could affect growth and sexual maturation such as steroids and anti-epileptic drugs; HIV-infected males (aged 10–19 years) with chronic diseases like bronchial asthma, diabetes mellitus, sickle cell anemia, cancer, chronic kidney disease, or other chronic cardiac, respiratory, renal, and endocrine disorders; HIV-negative males (aged 10–19 years) with similar chronic diseases; and HIV-negative males (aged 10–19 years) on similar long-term medications that could affect growth and sexual maturation. After informed consent from parents/caregivers and participants’ assent, the perinatally HIV-infected males and their sex-and age-matched HIV-negative controls were recruited by consecutive sampling in the Pediatric HIV and the Pediatric Out-Patient Clinics, respectively until the desired sample size was achieved.
Study procedure
A case-record form that required information about the subjects’ socio-demographic profile, and other relevant data extracted from their hospital records, was completed during the study. The social classification of the study participants was based on the proposed method that utilizes parental education and occupation [
24]. The social classes were re-grouped as the upper class (classes 1 and 2), middle class (class 3), and lower class (classes 4 and 5). The participants’ physical growth characteristics were assessed with height and weight measurements by one of the authors (CON) according to standardized procedures. BMI was calculated using the formula: weight (kg)/height (m
2). The weight-for-age, height-for-age, and Z scores for weight, height, and BMI derived from WHO reference values and WHO AnthroPlus software was obtained. The sexual maturity rating of the participants was conducted manually by CON using a Prader orchidometer to measure the testicular volume and standardized photographs to grade the pubic hair pattern. The participants’ pubertal stages were also assessed by CON, based on the proposed method by Marshall and Tanner [
25]. Using pubic hair, the staging comprised Stage 1 (PH1): no hair, Stage 2 (PH2): scanty, long, and slightly pigmented hair, Stage 3 (PH3): darker, starting to curl, small amounts of hair, Stage 4 (PH4): resembling adult-type but less quantity, coarse, and Stage 5 (PH5): adult distribution and spread to the medial surfaces of the thighs. For testicular volume (average volume), the staging was made up of Stage 1 (G1):3 ml. (< 4 ml.), Stage 2 (G2): 4–6 ml. (4 ml.), Stage 3 (G3): 6–12 ml. (10 ml.), Stage 4 (G4): 12–20 ml. (16 ml.), and Stage 5 (G5) : >20 ml. (25 ml.).
Ethical considerations
Study participants were only enrolled after consent and assent were obtained from the parents/guardians and the participants, respectively. Confidentiality was emphasized and maintained throughout the study. Participants were anonymized and identified with coded initials on the case-record forms.
Data analysis
We conducted data analysis using the Statistical Package for Social Sciences (SPSS) version 25 (Chicago Illinois) for Windows. Data were scrutinized for incorrectly filled information and cleaned. The normality of data distribution was checked using the Shapiro-Wilk test. The results were displayed in frequencies, charts, and tables as appropriate. Normally distributed data [e.g. height, weight, height-for-age Z-score (HAZ), body mass index-for-age Z-score (BAZ)] were analyzed by t-test. Non-normally distributed data (duration of HAART use in three groups of HIV-positive subjects categorized with their BMI as undernutrition, normal nutrition, and overnutrition) was analyzed by using the Kruskal-Wallis test. Comparisons of the anthropometric variables (e.g. height, weight, HAZ, and BAZ) between the HIV-infected subjects and the controls were also analyzed using an independent t-test. All tests of significance were two-tailed at a 5% level of significance (p = 0.05) and 95% confidence interval (CI).
Discussion
The physical growth and sexual maturation of perinatally-HIV infected male and female children have been well documented in studies conducted in developed and developing countries. In Nigeria, the few published studies that evaluated these outcomes were conducted in perinatally HIV-infected girls alone [
20,
23]. Thus, it is important to obtain data on similar outcomes among adolescent males seen in this clime.
In the present study, we assessed the physical growth and sexual maturity rating of perinatally HIV-infected adolescent males using anthropometric indices and grading of pubic-hair/testicular volume, respectively; and compared these parameters with those of age-matched HIV-negative controls. Firstly, we found that HIV-infected subjects had significantly lower weight and BMI Z-scores compared to their HIV-negative controls despite the use of HAART. Previous studies have reported varying degrees of growth deficits in height and weight among HIV-infected children [
21,
26‐
28]. For instance, some authors in South Africa documented suboptimal growth in adolescents with perinatally-acquired HIV infection: which appeared more pronounced in males than in females, in those who commenced HAART later in life, and in those who had baseline stunting [
21]. Other authors in the same country reported that perinatally HIV-infected children had early and sustained stunting, characterized by persistent low mean Z-scores for length-for-age and weight-for-age whereas those with rapidly progressive disease had both stunting and wasting [
26]. Additionally, a cohort study in the West African subregion noted that growth evolution was particularly strong among HIV-infected children on HAART within the first 2 years but declined after this period; the investigators specifically reported initial gains in WAZ and HAZ within 12 and 24 months, respectively which slowed down subsequently [
27]. Similarly, another cohort study in Malawi (Southern Africa) observed that although the growth trajectories of HIV-infected children on HAART showed sustained positive response among those continuing on therapy, normal WAZ and HAZ values were not eventually attained: implying that weight loss and stunting were the ultimate outcomes in these children [
28]. The findings of these studies [
21,
26‐
28] are consistent with those of the present study although we found no significant difference in HAZ values of HIV-infected and HIV-negative children: an observation that is in tandem with the reports of other authors [
29,
30]. We believe that the absence of a significant difference in HAZ values in our study cohorts may be explained by the prevalence of a high level of stunting in the general population in Nigeria [
31]. This high level of stunting means that differences in height between HIV-infected children and the general population may not, therefore, be significant. Based on our findings that showed a significant negative effect of HIV infection on weight and BMI Z-score, we suggest that these weight deficits can be attributed to HIV-induced immune dysfunction, attendant intercurrent infections, preferential decreases in lean body mass [
32], and growth hormone resistance [
33,
34]. Our finding also underscores the fact that regardless of racial and population differences or geographical location, HIV infection adversely affects weight gain. Although the exact primary mechanisms by which HIV impedes growth have not been fully established, secondary causes of growth faltering, such as dietary insufficiency and diarrhoeal illnesses, may be involved [
35]. Even without secondary infection, whole-body protein kinetics are altered with increased protein catabolism and synthesis of acute-phase reactants in response to viral replication, thus diverting energy away from the accrual of fat-free mass and growth [
35]. HIV-infected children have also been noted to accumulate bone density more slowly than non-infected children through direct infection of bone cells causing elevation of several cytokines (interleukin 1, interleukin 6, and tumor necrosis factor-α) that contribute to increased activity of osteoclasts [
36,
37]. Decreased growth hormone secretion has also been reported; but primary growth hormone deficiency is encountered only occasionally as basal growth hormone and stimulated growth hormone levels are normal in most HIV-infected children [
38,
39].
Secondly, our study noted significant delays in sexual maturation in the HIV-infected subjects using both the pubic hair development and testicular volume. None of the controls were found to be in stage 1 pubic hair development as opposed to fourteen subjects that were in the same stage. This difference statistically implied that the HIV-positive children were about ten times less likely to navigate from stage 1 to stage 2 of pubic hair development compared to their HIV-negative controls. These findings are in keeping with those of studies conducted in the United States [
17,
40] and in Uganda and Zimbabwe [
18], and underscore the negative effect of the chronicity of HIV infection on the onset, timing, and progression of sexual maturation. In the present study, the HIV-positive children surprisingly showed a tendency to achieve full testicular development (stage 5) earlier than the controls. This observation contrasts with the findings of other studies previously conducted in Europe [
41] and the United States [
42]. In one of the studies [
41], the ages of pubertal stages for HIV-1-infected girls and boys were at the > 97th percentile and 75-97th percentile, respectively of the controls (who were healthy children that provided the reference percentiles). We could not explain this particular disparity between our findings and those of these previous studies based on the available published literature. Non-adjustment for age in our statistical analysis may have contributed to the disparity. Our analysis of covariance showing the effect of two independent variables on testicular volume (after controlling for age) revealed that the covariate had a strong effect on the subjects’ testicular volume. In a Nigerian study conducted more than two decades ago to obtain normative data on the sexual development of Nigerian children, the authors noted that the onset of puberty in boys was between 9 and 15 years of age [
43]. Additionally, there was most often a close concordance between stages of testicular and pubic hair development at each age although stages of both features could be entirely discordant, as testicular development was always ahead of pubic hair development. In a more recent Nigerian study conducted four years ago, the concordance between testicular and pubic hair maturation was also reported by other authors, as the mean age of onset of pubic hair (stage 2) was 11 years in boys, while testicular development (stage 2) was seen at a mean age of 11 years [
44].
Generally, perinatal HIV-1 infection interferes with sexual maturation although the mechanisms by which this occurs are yet to be fully elucidated. However, the suggested mechanisms as previously mentioned include the dysfunction of the HPG axis [
12], and the ‘euthyroid sick syndrome’ [
13]. More importantly, it appears that the earlier the onset and severity of HIV infection, the greater the negative effects on pubertal growth: worsened by the vulnerability of adolescents to hormonal changes because of the immaturity of their HPG axis. This may partly explain why the duration of HAART use did not affect the delay in the early stages of pubic hair and testicular volume development in our study subjects.
Our study has some limitations. We used a Prader orchidometer to measure the testicular volume of the study participants. However, an ultrasound-scan measurement of the testicular volume may have provided more reliable data. Secondly, we conducted a cross-sectional study rather than a longitudinal study which would have better described the growth trajectory of perinatally HIV-infected children and their sexual maturation.
Therefore, we recommend a future research direction based on a longitudinal study with multiple interval assessments of sexual maturation throughout adolescence. This prospective study should be explored to better define the age of onset and progression through the different stages of puberty in HIV-infected children.
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