Demographic factors influence side preference and completeness in nonsyndromic orofacial clefts across multiethnic cohorts.

This observational cohort study evaluated demographic associations with cleft completeness in 3,561 individuals with nonsyndromic cleft lip with or without cleft palate (NSCL/P) from multiethnic populations in North and South America, Asia, and Africa. The primary outcome assessed side preference for completeness in nonsyndromic asymmetric bilateral and unilateral cleft lip with or without cleft palate. Secondary outcomes examined associations between cleft completeness, sex, ethnicity, and race.

In asymmetric bilateral cases, left-side completeness was significantly more frequent than right-side completeness (73.7% vs. 26.3%, p<0.001). No associations were observed for sex in this specific subgroup. Regarding race and ethnicity, a trend toward significance was observed (50.0% vs 25.5%, p=0.088). When comparing Hispanics versus non-Hispanics in symmetric bilateral and unilateral cases, Hispanics exhibited completeness more frequently (96.4% vs 89.5% for symmetric bilateral; 84.1% vs 79.7% for unilateral, p<0.001 for both). Additionally, Caucasians were less likely to exhibit complete clefts compared to Asians, Blacks, or other racial groups (68.7% vs 84.9% or 81.2% or 81.7%, p<0.001). In unilateral cases, no side preference was observed. Females more frequently presented with completeness than males (81.2% vs 76.6%, p=0.003).

No safety data, adverse events, or discontinuations were reported as the study focused on anatomical characteristics rather than pharmacological interventions. Limitations include the observational nature of the design, which precludes causal inference regarding demographic factors. These findings describe natural variation in cleft presentation across diverse populations but do not inform clinical management of cleft repair or prognosis beyond descriptive epidemiology.