Photographic grading to evaluate facial cleanliness and trachoma among children in Amhara region, Ethiopia

Abstract

Background: Promotion of facial cleanliness is recommended for the elimination of blinding trachoma, largely because of observational studies that have found an association between various measures of facial uncleanliness and trachoma. However, when a field grader assesses both facial cleanliness and trachoma, associations may be biased. Assessment of photographs of the face and conjunctiva by masked graders may provide a less biased estimate of the relationship between facial cleanliness and trachoma.

Methods: Face photographs, conjunctival photographs, and conjunctival swabs were obtained on a random sample of 0-9-year-old children from each of 40 communities in Amhara region, Ethiopia. Face photographs were assessed for the presence of seven measures of an unclean face (i.e., wet nasal discharge, dry nasal discharge, wet ocular discharge, dry ocular discharge, food, dust/dirt, and flies) by three independent masked photo-graders. Conjunctival photographs were similarly graded in a masked fashion for signs of clinically active trachoma. Conjunctival swabs were processed for Chlamydia trachomatis DNA.

Results: Of 2073 children with complete data, 808 (39%) had evidence of clinically active trachoma, 150 (7%) had evidence of ocular chlamydia infection, and 2524 (91%) had at least one measure of an unclean face. Dry ocular discharge had the strongest association with clinically active trachoma (age- and sex-adjusted prevalence ratio [PR] 1.4, 95% CI 1.2-1.6) and ocular chlamydia infection (PR 1.9, 95%CI 1.3-2.9), although significant associations were observed between each of the measures of facial uncleanliness and trachoma.

Conclusions: Masked assessment of face and conjunctival photographs confirmed prior observational studies that have noted associations between various measures of facial uncleanliness and trachoma. The causal relationship between facial uncleanliness and trachoma is unclear since many features used to measure facial cleanliness (e.g., ocular discharge, nasal discharge, and flies) could be consequences of antecedent ocular chlamydia infection.

Trial registration: NCT02754583, clinicaltrials.gov.

Fig 1. Participant flow.

A stratified random sample of approximately 30 children aged 0–5 years and 30 children aged 6–9 years from each of 40 communities in Ethiopia was selected for face photography, conjunctival photography, and conjunctival swabbing.

Fig 2. Overlap between various components of an unclean face.

Area-proportional Venn diagrams show the overlap in uncleanliness measures in a given child. The left panel depicts the overlap for (i) nasal discharge—either wet or dry, (ii) ocular discharge—either wet or dry, (iii) food or dust/dirt, and (iv) flies on the face; the middle panel depicts the overlap for wet and dry nasal discharge; and the right panel depicts the overlap for wet and dry ocular discharge.

Fig 3. Prevalence of trachoma outcomes stratified by various measures of an unclean face.

Each pair of bars represents the study population stratified by the presence (+) or absence (–) of a measure of facial uncleanliness, with the seven individual measures on the left and two composite measures on the right. Clinical trachoma outcomes are shown in the top panel and ocular chlamydia infection in the bottom panel.

Fig 4. Association between measures of facial uncleanliness and trachoma.

The points and bars represent age- and sex-adjusted prevalence ratios for each trachoma outcome and 95% confidence intervals. The numeric results used to make the figure are provided in S1 Table. Abbreviations: TF, trachomatous inflammation–follicular; TI, trachomatous inflammation–intense; CT, ocular C. trachomatis.

Fig 5. The association between trachoma outcomes and the total number of facial uncleanliness measures.

The reference value was a score of 0 (i.e., absence of all facial uncleanliness features). The numeric results used to make the figure are provided in S2 Table. Abbreviations: TF, trachomatous inflammation–follicular; TI, trachomatous inflammation–intense; CT, ocular C. trachomatis.

Fig 6. Association between measures of an unclean face with clinically active trachoma (i.e., TF and/or TI) in selected studies.

Points and bars represent odds ratios and 95% confidence intervals. Measures of association for the present study were re-calculated with logistic regression to improve comparability with other studies (S3 Table). Studies are listed in descending order of trachoma prevalence (provided in parentheses). Estimates produced by multivariable models are indicated with an asterisk. Studies assessing composite measures used different definitions of an unclean face, which are indicated in the shaded boxes (N/F = nasal discharge or flies on face; N/O = nasal or ocular discharge; N/O/D = nasal discharge, ocular discharge, or dirt; N/O/F/D = nasal discharge, ocular discharge, flies, or dirt).

Fig 7. Association between measures of an unclean face and ocular chlamydia in selected studies.

Points and bars represent odds ratios and 95% confidence intervals. Measures of association for the present study were re-calculated with logistic regression to improve comparability with other studies (S3 Table). Studies are listed in descending order of ocular chlamydia prevalence (provided in parentheses). Estimates produced by multivariable models are indicated with an asterisk.