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Body mass index as a predictor of sonographic visualization of the pediatric appendix
Cory M Pfeifer1, Luyu Xie2,3, Folefac D Atem3,4
1Department of Management, Policy, and Community Health, University of Texas Health Sciences Center, School of Public Health, 1200 Pressler St., Houston, TX, 77030, USA. Cory.Pfeifer@utsouthwestern.edu.
Insights
Higher body mass index (BMI) z-scores in children significantly decrease the likelihood of visualizing the appendix during ultrasound (US) exams. This finding is crucial for pediatric appendicitis diagnosis amid rising obesity rates.
Area of Science:
- Pediatric Radiology
- Medical Imaging
- Obesity Research
Background:
- Appendicitis diagnosis in children commonly relies on imaging, with ultrasound (US) as the initial choice.
- Increased body mass index (BMI) is a known challenge to US sensitivity for appendicitis.
- Pediatric obesity rates are rising, highlighting the public health significance of factors affecting diagnostic accuracy.
Purpose of the Study:
- To investigate the relationship between age-adjusted BMI z-scores and the sonographic visualization rate of the appendix in pediatric patients.
- To determine if higher BMI z-scores correlate with decreased appendix visualization on ultrasound.
Main Methods:
- Retrospective review of 500 pediatric appendicitis US exam reports with documented BMI.
- Stratification of patients into BMI z-score groups to compare appendix visualization frequencies.
- Logistic regression analysis to assess the odds of visualization by BMI z-score, adjusting for sex, ethnicity, insurance, and home language.
Main Results:
- Appendix visualization decreased as BMI z-score increased, with significantly lower rates in children with BMI z-score >2 (29.3%) compared to those with BMI z-score -1 to 1 (57.4%).
- Children with BMI z-score >2 had significantly lower odds of appendix visualization (aOR: 0.21, P<0.0001).
- Boys had higher visualization rates than girls (61.1% vs. 46.2%, P<0.05), with no significant effect modification by ethnicity, insurance, or home language.
Conclusions:
- Increasing BMI z-scores are independently associated with reduced sonographic visualization of the appendix in children.
- These findings underscore the impact of the pediatric obesity epidemic on diagnostic imaging accuracy.
- Radiologists should consider higher BMI as a factor potentially limiting US efficacy in pediatric appendicitis evaluation.
Background:
Appendicitis is a common condition that is often confirmed with imaging. Ultrasound (US) is recommended as the first radiologic test in the work-up of appendicitis in children. Increased body mass index (BMI) has been implicated as a limiting factor to the sensitivity of US. This has drastic public health ramifications, as pediatric obesity has been increasing at alarming rates.
Objective:
The purpose of this study is to compare age-adjusted BMI z-scores to the frequency of sonographic visualization of the appendix.
Materials And Methods:
A retrospective review of 500 consecutive reports of US exams ordered for appendicitis in patients with a documented BMI was performed. Patients were stratified by BMI z-score based on, and the visualization frequency of the appendix was compared to the BMI z-score group. A logistic regression analysis generated the odds of visualization of the appendix by BMI z-score group. Primary home language, ethnicity, sex and insurance status were included in the logistic regression model to assess these characteristics as potential effect modifiers.
Results:
Of the 500 patients, 52.4% were male, 56.4% were Hispanic and 62.0% had government insurance. BMI z-score distribution groups were as follows: 4.2% were <-2, 8.0% were -2 to -1, 49.8% were -1 to 1, 26.4% were 1 to 2 and 11.6% were >2. The visualization frequency was 61.1% for boys and 46.2% for girls (P<0.05). Visualization frequency by BMI z-score group was as follows: 85.7% for <2, 72.5% for -2 to -1, 57.4% for -1 to 1, 47.7% for 1 to 2 and 29.3% for >2. Children with a BMI z-score greater than 2 were less likely to have a US with visualization of the appendix compared to children with a BMI z-score between -1 and 1 (adjusted odds ratio [aOR]: 0.21, 95% CI: 0.11-0.40, P<0.0001). Boys were more likely than girls to have a US with visualization of the appendix (aOR: 1.90, 95% CI: 1.29-2.80, P=0.001). There was no effect from insurance status, ethnicity or primary home language.
Conclusion:
Findings show that as the BMI z-score increased, sonographic visualization of the appendix decreased even after adjusting for demographic differences. These findings have implications for pediatric radiology practice in light of the worsening obesity epidemic.
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