Discussion
Our findings indicate that several proximal, medial and distal factors
in a child’s ecosystem may impact on the risk of childhood PTB and
nutritional status. Proximal risk factors for childhood TB included sex
and previous hospitalization. Consistent with this, young male South
African children have been reported to be at higher risk for tuberculin
skin test conversion, TB disease and LRTI, which may reflect a
biological susceptibility due to hormonal or other
factors25. Medial risk factors included caregiver
tobacco use. While caregiver tobacco use was not associated with
childhood PTB beyond univariate analyses, caregiver tobacco use is a
known risk factor for PTB. Tuberculosis and second-hand smoke exposure
have a severe negative impact on the respiratory system. A meta-analysis
conducted on second hand smoke (SHS) exposure and TB risk has shown that
children have more than 3-fold increased risk of SHS-associated active
TB compared to those not exposed to SHS26. Similarly,
caregiver psychological distress was not associated with childhood PTB.
However, severe psychological distress among caregivers was common. This
may reflect the burden of caring for a child with illness and
environmental stressors inherent in living in poverty1;
3. The high number of caregivers surviving on a subsistence budget in
our study may compound the elevated levels of psychological distress.
This is consistent with the literature, that has found an association
between caregiver psychological distress and socioeconomic
status8.
Finally, we examined distal factors linked to childhood TB. Caregivers
with less than 10 years of schooling, a monthly income of less than
<$68 per month were distal determinants associated with
childhood TB. As evidenced through the outcome of mycobacteriologically
confirmed TB limited monetary resources and educational attainment
underscore the structural barriers some caregivers experience when
caring for a child with TB.
Malnutrition is a known risk factor for childhood TB5;
however, this link was only evidenced by our findings that low-weight or
low-height for age were associated with childhood TB in the univariate
analyses. This may also reflect that our control group were children
sick with non-TB respiratory illnesses, for which malnutrition may also
be a risk factor. Medial factors observed for the outcome of TB
diagnostic category and TB treatment related to caregiver
characteristics were also associated with childhood malnutrition at
baseline. Caregiver smoking was an important risk factor for childhood
malnutrition with a 3-fold increased risk for childhood malnutrition.
Malnutrition, was more than twice as likely to be present in children of
caregivers who suffered from severe psychological distress. Given the
nuanced links between childhood TB and proximal, medial and distal risk
factors in our data, child malnutrition appears to be a distal risk
factor for childhood TB that needs further exploration. Additional
studies using a child ecosystem approach are needed to confirm our
findings in relation to child nutrition.
The proximal, medial and distal factors identified in our ecosystem
analysis help to provide an important context to the high prevalence of
TB among children in this population. Promisingly, adherence in this
study was extremely high. Despite the high adherence rates, rates of
lost-to-follow-up shed light on a subpopulation in our study that could
benefit from family-ecosystem oriented interventions. Of the 6% of
children that did not attend the 3-month visit, loss-to-follow-up was
associated with proximal, medial and distal factors associated with
childhood TB and childhood malnutrition that we identified using a
childhood ecosystem framework. These findings indicate that caregivers
with less schooling and suboptimal mental health may need additional
support from healthcare systems to ensure that adherence for their
children’s TB treatment stays high.
The high rates of psychological distress among caregivers is concerning.
These data are consistent with reported rates of psychological distress
in studies of adult TB patients in South Africa9-11,
and how this may relate to childhood TB including adherence to follow-up
visits is an avenue that warrants further exploration.
Limitations include that questionnaires were self-completed by
caregivers. As such, prevalence of smoking, alcohol use or psychological
distress may have been underestimated.That notwithstanding, a strong
association was shown between these risk factors as organized through
the childhood ecosystem approach and TB diagnosis, TB treatment and
childhood malnutrition. Second, only 69% of the caregivers of children
consented to completing the questionnaires. Caregivers that elected to
not participate in this study may have been less healthy [Supplemental
Table VII]. Our reported prevalence rates represent the minimum
prevalence for psychological distress or substance use. Reasons for not
consenting were not recorded. No differences in age, level of schooling
or gender between those that consented and those that did not consent
were found.
Despite these limitations, the findings emerging from this study provide
a clearer picture of risks for childhood TB. Our findings highlight the
need for broad interventions to provide appropriate support protection
strategies to reduce this burden, such as labor market supports such as
job training or temporary subsidies to families in need. Additional
research is required to explore the impact of the child ecosystem during
transitional points in the development trajectory. For example, the role
of family, peers, and individuals in the educational ecosystem may have
varying points of prominence depending on what stage of development the
child is in. Interventions should consider developmental milestones that
may be leveraged for maximum intervention effect. Such studies may
provide a more nuanced understanding and approach to risk reduction of
transmission, diagnosis or management of TB.