Prevalence of Congenital Anomalies of the Upper Limbs in Brazil: a descriptive cross-sectional study

ABSTRACT BACKGROUND: Congenital Anomalies of the Upper Limb (CAUL) are a group of structural or functional abnormalities that develop during intrauterine life and can lead to limb dysfunction. OBJECTIVES: To analyze the prevalence of congenital anomalies of the upper limbs in Brazil and assess maternal and neonatal variables. DESIGN AND SETTING: A cross-sectional, descriptive study was conducted on congenital upper limb malformations among live births across Brazil. METHODS: The study spanned from 2010 to 2019. Data were sourced from the Department of Informatics of the Unified Health System (DATASUS) and the Live Birth Information System (SINASC) portal. Analyses focused on the information reported in field 41 of the Live Birth Declaration Form entered into the computerized system. RESULTS: The most common anomaly in Brazil was supernumerary fingers, classified as ICD-Q69.0, affecting 11,708 children, with a prevalence of 4.02 per 10,000 live births. Mothers aged over 40 years had a 36% higher prevalence of having children with CAUL than mothers under 40 years old (OR = 1.36; 95% CI 1.19-1.56). Newborns weighing ≥ 2,499 g were 2.64 times more likely to have CAUL compared to those weighing ≥ 2,500 g (OR = 2.64; 95% CI 2.55-2.73). CONCLUSION: There was an observed increase in the reporting of CAUL cases over the decade studied. This trend serves as an alert for health agencies, as understanding the prevalence of CAUL and its associated factors is crucial for preventive medicine.

Epidemiological data on CAUL are vital for the development, planning, and monitoring of public health strategies.
Studies on etiology and prevention depend on high-quality epidemiological data. 8The accuracy of an epidemiological study hinges on understanding the studied population and the authenticity of the collected data. 9This study hypothesizes that the national prevalence data for CAUL are consistent with those collected globally.

OBJECTIVE
The objective of this study was to analyze the prevalence of CAUL in Brazil from 2010 to 2019, utilizing the DATASUS database, and to evaluate the associated maternal and neonatal variables.

Research design
This descriptive cross-sectional study examined cases of CAUL in newborns in Brazil from 2010 to 2019, adhering to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

Data-gathering period
Data were collected from September to October 2021 and extracted from the Department of Informatics of the Unified Health System -DATASUS (available at http://www2.datasus.gov.br). 10This database compiles information from the mandatory Live Birth Certificate (DNV) for all live births in Brazil, maintained in the SINASC system.

Selection criteria
The study variables included demographic details, types of upper limb congenital anomalies, and maternal and newborn variables as recorded in DATASUS.The data from the live birth certificates, which contain 41 fields divided into seven blocks, were utilized.
Field 41 specifies congenital anomalies as noted by the delivery personnel or a neonatologist.Following Chapter XVII, titled "Congenital Malformations, Deformities, and Chromosomal Abnormalit" all anomalies were recorded non-hierarchically, with a detailed description of the codes from the International Classification of Diseases (ICD-10).

Data-gathering
The Swanson classification was employed to categorize CAUL, 11  All ICD-10 codes corresponding to CAUL diagnosed at birth were selected.Diagnoses were grouped to categorize anomalies according to related pathologies (Table 1).
The variables of interest selected for analysis pertained to the period and place of birth, maternal data (age, education, gestational duration, type of delivery, type of pregnancy, and prenatal visits), and newborn variables (Apgar scores at 1 and 5 min, sex, birth weight, and race/ethnicity).No discernible patterns of cyclic or irregular components were identified during the subjective analysis of the graph; therefore, no cyclical analysis was performed.As the source data were annual, it was impossible to identify a seasonal component throughout the year.Each year of occurrence was used as the independent variable, and the ratio of live births with upper limb malformations to the total number of live births per year was used as the dependent variable.An overall analysis was conducted for Brazil, and a regional analysis was performed for the country (North, South, East, and West).For statistical inference, a statistically significant difference was considered at a type I error rate of P < 0.05.The number of newborns with CAUL was analyzed separately by ICD codes and country.The national prevalence of CAUL was 7.5 per 10,000 LBs.The most prevalent anomaly was supernumerary fingers, represented by ICD-Q69.0, affecting 11,708 children (a prevalence of 4.02 per 10,000 live births).In contrast, the anomaly with the lowest national prevalence was the longitudinal reduction defect of the ulna, represented by ICD-Q71.5, with a prevalence of 0.01 per 10,000 live births (Table 2).
Regional prevalence of CAUL per 10,000 LBs by ICD-10 code from 2010 to 2019, showed the Southeast having the highest rate of 9.15.The Northeast had the second-highest prevalence (Table 2).
The anomaly of supernumerary fingers (ICD-Q69.0)had the highest regional prevalence in the Southeast, at 5.34 per 10,000 LBs.
The congenital hand deformity (ICD-Q68.1),the second most prevalent anomaly nationwide, had its highest prevalence in the Southern region, at 1.14 per 10,000 live births (Table 3).
Duplication defects, representing a group of CAUL, had the highest prevalence in all studied years, increasing from 3.6 cases per 10,000 LBs in 2010 to 4.8 in 2019.
Maternal and newborn variables were analyzed and are detailed in Tables 4 and 5 5).
Through linear trend and moving average (MA) analysis of cases, an increase in prevalence was observed during the study period, with approximately 2.2 CAUL cases per 10,000 LBs when comparing 2010 and 2019.Linear regression analysis of the adjusted data for prevalence per 10,000 LBs showed an increase of 0.185 per year, with a standard error of 0.021.Thus, there was a linear trend of an increase in the prevalence of 0.206 (95% CI 0.133-0.237)CAUL per 10,000 LBs per year (P < 0.001).Notably, graph visualization demonstrated a linear trend component of increased CAUL prevalence when analyzing raw data over the years and smoothed moving averages (Figure 1).Remarkably, the graph visualization showed a linear trend component of increased CAUL prevalence when analyzing raw data over the years and the smoothed moving average (Figure 2).

DISCUSSION
This study represents the first prevalence analysis of CAUL in Brazil, utilizing a national database to identify associated factors in newborns (NBs) and mothers.The national prevalence of upper limb anomalies between 2010 and 2019 was 7.  to 2010, finding a CAUL prevalence of 27.2 cases per 10,000 births. 12other study on the epidemiology of congenital limb anomalies in Japan estimated a prevalence of 4.15 per 10,000 LBs. 13 In Finland, the national incidence of CAUL was observed at 5.25 per 10,000 LBs between 1993 and 2005, with these anomalies often associated with other congenital disabilities in up to two-thirds of cases. 14e data presented in this study are consistent with global findings on CAUL prevalence.In our analysis, the ICD code for supernumerary fingers (Q69.0) had the highest absolute number of cases with 11,708 and the highest prevalence at 4.02 cases per 10,000 LBs, comparable to findings in New York, where polydactyly was the most common CAUL, totaling 12,418 cases at a rate of 23.4 per 10,000 LB. 12 Our study also analyzed maternal and newborn factors and their associations with CAUL.The findings indicate higher rates of CAUL in mothers over 40 years old, in preterm births (before 37 weeks), during multiple pregnancies, and among women who had fewer than seven prenatal visits.
In Tangará da Serra, Brazil, between 2006 and 2016, a study demonstrated a higher prevalence of CAs in newborns of mothers over 35 years old, an expected finding as maternal age is a primary risk factor for chromosomal anomalies. 15om 2010 to 2014, São Paulo reported 819,018 live births, 14,657 (1.6%) of which had CAs, predominantly osteoarticular and circulatory.An association was observed between congenital anomalies and maternal age over 40 years, multiple pregnancies, and newborns with low birth weight 16 , which aligns with our own results.In a study conducted in Rio de Janeiro between 1990 and 2002, the incidence of CAs in male newborns was higher, particularly in those born before 37 weeks with a birth weight of less than 2,500g 19 .Another study in Vale Paraíba Paulista identified a statistically significant association between gestational duration (< 37 weeks), lower Apgar scores (< 7), low birth weight (< 2,500 g), and CAs (P < 0.001). 18veral instruments are available for collecting epidemiological data to integrate and unify information on notifications of congenital anomalies.Established in 1974, the "International Clearinghouse for Birth Defects Surveillance and Research" (ICBDSR) aims to prevent congenital disabilities and currently includes 42 member programs worldwide. 21EUROCAT, a European network for epidemiological surveillance founded in 1979, now has 21 participating countries. 23This system has developed and matured over the past two decades through the standardization of definitions, diagnoses, and terminology. 24 Latin America, the Collaborative Latin American Study of Congenital Malformations, founded in 1967, covers South America, Costa Rica, and the Dominican Republic, employing a case-control methodology. 20However, a significant limitation in Brazil is the low participation of national maternity hospitals in this program, with only four of the 35 registered hospitals located in Brazil. 22 utilized data from DATASUS via the SINASC portal, a nationwide computerized data collection system where all birth-related data in Brazil are recorded.Given the country's vast size, this method offers rapid and convenient data collection and integration for public health, facilitating better analysis.
This study has limitations that should be considered when interpreting the results.Despite its nationwide scope and mandatory reporting, the SINASC database may contain inconsistencies, such as possible duplications, and does not allow for the individualization of cases, which would enable a more detailed statistical analysis of variables.
The cross-sectional nature of the study and the lack of individual case details regarding the exposure factor and disease at a specific time prevent establishing any cause-and-effect relationship between congenital anomalies and the analyzed variables.
The results underscore the significance of this research by pro- This nationwide study was conducted in a country with a continental span.Nearly 30 million cases over ten years were analyzed.A national computerized reporting system that allows for the rapid and precise exchange of information across distant states and municipalities is invaluable.

CONCLUSION
The prevalence of CAUL in Brazil between 2010 and 2019 was grouping similar deficiency patterns based on specific embryological faults.The categories included: (I) failure of formation, (II) failure of differentiation, (III) duplication, (IV) overgrowth, (V) undergrowth, (VI) congenital constriction band syndrome, and (VII) generalized skeletal abnormalities.Anomalies were grouped according to their corresponding ICD-10 codes.

Figure 1 .
Figure 1.Linear trend based on the moving average -prevalence of CAUL for every 10,000 LB (2010-2019) viding a representative overview of the burden of CAUL among live births in Brazil.Multiple analyses facilitated an understanding of the variables associated with congenital anomalies.Enhancing the diagnosis of CAUL and ensuring the accurate completion of the Live Birth Certificate (DNV) through the ongoing education of health professionals responsible for record-keeping is a strategy that should be implemented by the Health Departments of Brazilian states to minimize the incidence of missing or inaccurate data, thereby reducing underreporting.

7. 5
per 10,000 LBs.ICD Q69.0, representing supernumerary fingers, is the most common CAUL in our population.The maternal factors associated with CAUL included being under 40 years of age, undergoing cesarean delivery, having fewer than three prenatal consultations, having less than 11 years of education, a gestational age of 36 weeks or less, and experiencing multiple pregnancies.For newborns, associated factors included a birth weight of 2,500 grams or less, male gender, Black race, and Apgar scores of 7 or less at both the 1st and 5th minutes.A consistent upward trend in CAUL case reports has been observed over the past decade.This study can inform more effective public health policy strategies.However, further research is essential to enhance our understanding of the underlying causes of the increase in CAUL cases, particularly concerning supernumerary fingers and their implications.

Table 2 .
Prevalence of congenital malformations of the upper limbs by regions of Brazil for every 10 thousand LB(2010-2019) . Concerning maternal age at the time of delivery, the majority of cases did not specify the age; however, children born to mothers over 40 years old exhibited a prevalence 1.36 times (or 36%) higher than those born to mothers under 40 years of age (OR = 1.36; 95% CI 1.19-1.56).In terms of delivery type, Cesarean sections accounted for 12,418 cases of CAUL, with a prevalence of 7.6 per 10,000 LBs.In these cases, the prevalence of children born with CAUL was 1.07 times (or 7%) higher than in those born via spontaneous delivery (OR = 1.07; 95% CI 1.04-1.10).The number of prenatal visits was often unknown.Mothers who had three or fewer prenatal visits showed a 1.37 times (or 37%) higher prevalence of having children with CAUL compared to mothers who had four or more prenatal visits (OR = 1.37; 95% CI 1.27-1.48).Mothers with 11 years of education or less had a 1.22 times (or 22%) higher prevalence of having children with CAUL compared to those with 12 or more years of education (OR = 1.22; 95% CI 1.18-1.27).ing ≤ 2,499 g.Newborns in this weight range had a prevalence 2.64 times (or 64%) higher for CAUL compared to newborns with a birth weight ≥ 2,500 g (OR = 2.64; 95% CI 2.55-2.73).Male newborns exhibited a 23% higher prevalence of CAUL than female newborns (OR = 1.23; 95% CI 1.17-1.30).Black newborns (*) LB= live births; (*) CAUL=congenital anomaly of the upper limbs

Table 3 .
Prevalence de CAUL by region (per 10,000 LB) by ICD-10 code between 2010 and 2019 Regions of Brazil N-North; NE-northeast; CO-west center; SE-Southeast; S -South Prevalence of CAUL according to maternal variables in Brazil for every 10,000 LB -2010-2019