Evaluation of the health-related quality of life of children in Schistosoma haematobium-endemic communities in Kenya: a cross-sectional study.

BACKGROUND: Schistosomiasis remains a global public health challenge, with 93% of the ~237 million infections occurring in sub-Saharan Africa. Though rarely fatal, its recurring nature makes it a lifetime disorder with significant chronic health burdens. Much of its negative health impact is due to non-specific conditions such as anemia, undernutrition, pain, exercise intolerance, poor school performance, and decreased work capacity. This makes it difficult to estimate the disease burden specific to schistosomiasis using the standard DALY metric. METHODOLOGY/PRINCIPAL FINDINGS: In our study, we used Pediatric Quality of Life Inventory (PedsQL), a modular instrument available for ages 2-18 years, to assess health-related quality of life (HrQoL) among children living in a Schistosoma haematobium-endemic area in coastal Kenya. The PedsQL questionnaires were administered by interview to children aged 5-18 years (and their parents) in five villages spread across three districts. HrQoL (total score) was significantly lower in villages with high prevalence of S. haematobium (-4.0%, p<0.001) and among the lower socioeconomic quartiles (-2.0%, p<0.05). A greater effect was seen in the psychosocial scales as compared to the physical function scale. In moderate prevalence villages, detection of any parasite eggs in the urine was associated with a significant 2.1% (p<0.05) reduction in total score. The PedsQL reliabilities were generally high (Cronbach alphas ≥0.70), floor effects were acceptable, and identification of children from low socioeconomic standing was valid. CONCLUSIONS/SIGNIFICANCE: We conclude that exposure to urogenital schistosomiasis is associated with a 2-4% reduction in HrQoL. Further research is warranted to determine the reproducibility and responsiveness properties of QoL testing in relation to schistosomiasis. We anticipate that a case definition based on more sensitive parasitological diagnosis among younger children will better define the immediate and long-term HrQoL impact of Schistosoma infection

Feasibility and utility of PedsQL SF15 for children initially <i>S. haematobium</i> egg-positive or egg-negative^a.

a<p>Cases were those children initially found to have <i>S. haematobium</i> eggs on urine filtration during parasitological surveys. Controls were children who had been egg-negative. N.B. The PedsQL SF15 was administered 3–16 months after completion of testing and treatment for infection.</p>b<p>% Floor/Ceiling = the percentage of scores at the extremes of the scaling range. Floor or ceiling effects in the range of 1–15% are acceptable while those >15% [<b>in BOLD</b>] are considered to provide less precise estimates.</p

Agreement between self-report and parent proxy-report PedsQL SF15 score scales.

<p>Inter-class correlation (ICC) values for survey results are considered as poor to fair agreement (≤0.40), moderate agreement (0.41–0.60), good agreement (0.61–0.80) or excellent agreement (0.81–1.00) <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002106#pntd.0002106-Bartko1" target="_blank">[54]</a>. <b>Bold face</b> indicates moderate or better agreement between child and parent-proxy.</p>a<p>Abbreviation: Sh, <i>Schistosoma haematobium.</i></p

Map of the study area showing location of study villages in Coast Province, Kenya.

<p>Map of the study area showing location of study villages in Coast Province, Kenya.</p

Multivariable GEE modeling of self-reported total HrQoL scores adjusting for measured covariates^a.

<p>In each case, the initial model of PedsQL SF15 score included the following explanatory variables: sex, age group, village type (high- vs. lower-endemicity), socioeconomic standing, current <i>Schistosoma</i> infection, current hookworm infection, anemia, presence of growth stunting, and nutritional wasting. Generalized multivariable linear modeling, adjusted for covariance at the village level using GEE estimation (SPSS) used stepwise backward removal of non-significant variables to create ‘best fit’ parsimonious models (based on information criteria) retaining explanatory variables with P-values<0.1. Multiply-adjusted parameter estimates are reported (with 95% CI and corresponding P-values) for covariates remaining in the final models. Scale for the HrQoL scale output variable was set at 100, so that the parameter estimates reflect percentage changes in overall HrQoL as estimated by the PedsQL instrument.</p>a<p>Abbreviations: GEE, Generalized Estimating Equations; HrQoL, Health-related quality of life; Sh, <i>Schistosoma haematobium</i>; CI, Confidence Interval; SES, socio-economic standing.</p>b<p>Reference group for comparison was top 50% SES.</p>c<p>Stunting: height-for-age Z score (HAZ) ≤−2.</p>d<p>Wasting: BMI-for-age Z score (BAZ) ≤−2.</p

Characteristics of the study population by age group.

<p>Abbreviations: SD, standard deviation; SES, socioeconomic standing; <i>Sh</i>+, <i>Schistosoma haematobium</i> egg-positivity.</p>a<p>P value refers to significance of differences among the villages by Mann-Whitney U test, ANOVA, or chi-square testing.</p>b<p>Anemia based on WHO age-specific hemoglobin (Hb) criteria <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002106#pntd.0002106-WHOCDC1" target="_blank">[40]</a>: for ages <12 years, Hb<11.5 g/dl; for ages ≥12 years, Hb<12 g/dl; but for males ≥15 years, Hb<13 g/dl.</p>c<p>Stunting: in height-for-age Z score (HAZ)≤−2.</p>d<p>Wasting: BMI-for-age Z score (BAZ)≤−2.</p

Multivariable GEE modeling of HrQoL psychosocial scores adjusting for measured covariates^a.

<p>In each case, the initial model of PedsQL SF15 score included the following explanatory variables: sex, age group, village type (high- vs. lower-endemicity), socioeconomic standing, current <i>Schistosoma</i> infection, current hookworm infection, anemia, presence of growth stunting, and nutritional wasting. Generalized multivariable linear modeling, adjusted for covariance at the village level using GEE estimation (SPSS) used stepwise backward removal of non-significant variables to create ‘best fit’ parsimonious models (based on information criteria) retaining explanatory variables with P-values<0.1. Multiply-adjusted parameter estimates are reported (with 95% CI and corresponding P-values) for covariates remaining in the final models. Scale for the HrQoL scale output variable was set at 100, so that the parameter estimates reflect percentage changes in overall HrQoL as estimated by the PedsQL instrument.</p>a<p>Abbreviations: GEE, Generalized Estimating Equations; HrQoL, Health-related quality of life; Sh, <i>Schistosoma haematobium</i>; CI, Confidence Interval; SES, socio-economic standing.</p>b<p>Reference group for comparison was top 50% SES.</p>c<p>Stunting: height-for-age Z score (HAZ) ≤−2.</p>d<p>Wasting: BMI-for-age Z score (BAZ) ≤−2.</p>e<p>Reference group was 5–7 year olds.</p

PedsQL SF15 scores for study participants stratified according to <i>S. haematobium</i> egg-positive <i>vs.</i> egg-negative status.

a<p>Sh egg-positive were those children initially found to have <i>S. haematobium</i> eggs on urine filtration during parasitological surveys. <i>Sh</i> egg –negative were children who had been egg-negative. N.B. The PedsQL SF15 was administered after testing and treatment for infection. (n = 802 for child self-report and 765 for parent proxy report).</p>b<p>Effect size = (difference between cases and controls)/SD of controls. Effect sizes are typically designated as small (0.20–0.49), medium (0.50–0.79), or large (≥0.80).</p>c<p><i>P</i><0.05 (independent sample t-test).</p

Flow chart of study participation.

<p>Numbers of children by village at enrolment, at parasitological and anthropometric testing, and at HrQoL assessment.</p

PedsQL SF15 score scales for children and parents within high and moderate prevalence villages.

a<p>Sh egg +ve were those children initially found to have <i>S. haematobium</i> eggs on urine filtration during parasitological surveys. <i>Sh</i> egg −ve were children who had been egg-negative. N.B. The PedsQL SF15 was administered after testing and treatment for infection.</p>b<p>Effect size = (difference between cases and controls)/SD of controls. Effect sizes are designated as small (.20), medium (.50), and large (.80).</p>*<p>p<0.05 (independent samples t-test).</p