Factors predictive of Ponseti casting for treating clubfoot: analysis of Bayesian Poisson regression model

OBJECTIVE

Clubfoot is a growing public health concern in Bangladesh, with the incidence of approximately 0.64 to 6.8 in every 1000 live births. For over a decade, Ponseti method has been considered a gold standard for treating the clubfoot. Despite few studies have been estimating the number of casts required to correct the clubfoot deformities by Ponseti method, the subject of interest has always remained. Therefore, this current study aimed to investigate the significant predictive factors for the number of casts required to correct congenital clubfoot.

PATIENTS AND METHODS

In this retrospective cohort study, we used Bayesian Poisson Regression Model to investigate the influencing factors that could predict how many casts are needed to correct the clubfoot. We included 69 patients with 99 affected feet, who completed their corrective phase of treatment in the Ponseti method. For this cohort study, we integrated only pre-tenotomy casting data with no age restrictions. We used Bayesian Poisson regression analysis technique to estimate the predictive factors.

RESULTS

In Bayesian Poisson model, age was the most influencing predictive factor (24.3%) for increasing the number of castings to correct the clubfoot deformity. The clubfoot offspring of the ≤1-year-old was positive, and the incidence rate increased significantly with the casting number. The number of Ponseti casts in male clubfoot children was 28% higher than in female, and this was marginally statistically significant. There was no marked change estimated in the pattern of clubfoot, foot involvement and Pirani score of the severity.

CONCLUSIONS

We concluded that the age factor may influence the number of casts required for the correction of clubfoot and specifically ≤ 1-year-old children are highly impacted. Treating clubfoot at an early age is suggested in this study to increase the success of clubfoot treatment and decrease the risk of relapse.

Arsenic exposure and cell-mediated immunity in pre-school children in rural Bangladesh

Prenatal arsenic exposure has been associated with reduced thymic index and increased morbidity in infants, indicating arsenic-related impaired immune function. We aimed at elucidating potential effects of pre- and postnatal arsenic exposure on cell-mediated immune function in pre-school aged children. Children born in a prospective mother-child cohort in rural Bangladesh were followed up at 4.5 years of age (n = 577). Arsenic exposure was assessed by concentrations of arsenic metabolites (U-As) in child urine and maternal urine during pregnancy, using high-performance liquid chromatography online with inductively coupled plasma mass spectrometry. For assessment of delayed type hypersensitivity response, an intradermal injection of purified protein derivative (PPD) was given to Bacillus Calmette-Guerin vaccinated children. The diameter (mm) of induration was measured after 48-72 h. Plasma concentrations of 27 cytokines were analyzed by a multiplex cytokine assay. Children's concurrent, but not prenatal, arsenic exposure was associated with a weaker response to the injected PPD. The risk ratio (RR) of not responding to PPD (induration <5 mm) was 1.37 (95% confidence interval (CI): 1.07, 1.74) in children in the highest quartile of U-As (range 126-1228 μg/l), compared with the lowest (range 12-34 μg/l). The p for trend across the quartiles was 0.003. The association was stronger in undernourished children. Children's U-As in tertiles was inversely associated with two out of 27 cytokines only, i.e., IL-2 and TNF-α, both Th1 cytokines (in the highest tertile, regression coefficients (95% CI): -1.57 (-2.56, -0.57) and -4.53 (-8.62, -0.42), respectively), but not with Th2 cytokines. These associations were particularly strong in children with recent infections. In conclusion, elevated childhood arsenic exposure appeared to reduce cell-mediated immunity, possibly linked to reduced concentrations of Th1 cytokines.