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PA student assessment of body mass index in children using visual cues

Berg, Gina M. PhD, MBA; Casper, Paul PA-C; Ohlman, Evan PA-C; Schulte, Justin PA-C; Ahlers-Schmidt, Carolyn R. PhD; Nyberg, Sue PA-C, MPH; Ekengren, Francie MD

Journal of the American Academy of PAs: October 2017 - Volume 30 - Issue 10 - p 37–41
doi: 10.1097/01.JAA.0000524710.94848.98
Original Research

Objective: Pediatric weight or body mass index often is underestimated by providers when relying solely upon visual cues. This study sought to determine physician assistant (PA) students' and recent graduates' ability to accurately assess BMI for age in patients ages 3 to 5 years using visual cues.

Methods: PA students and recent graduates visually assessed pictures of three children ages 3 to 5 years—one obese, one overweight, and one with healthy weight—for BMI categorization via online survey. Responses were scored for accuracy.

Results: Ninety-eight PA students and recent graduates completed the assessment. Accuracy for BMI categorization was low, especially in the obese and overweight children for visual assessment alone. Accuracy improved slightly when height and weight data were provided.

Conclusions: PA student and recent graduate visual assessment for categorization of BMI is unreliable, similar to studies with other providers. PAs should be aware of discrepancy and not rely on visual assessment to determine weight-related interventions.

Gina M. Berg is a research associate professor in the Department of Family and Community Medicine at the University of Kansas School of Medicine in Wichita, Kans. Paul Casper, Evan Ohlman, and Justin Schulte are recent graduates of the PA program at Wichita (Kans.) State University. Carolyn R. Ahlers-Schmidt is a research associate professor at the University of Kansas School of Medicine in Wichita. Sue Nyberg is a professor in the PA program at Wichita State University. Francie Ekengren is chief medical officer at Wesley Medical Center in Wichita. The authors have disclosed no potential conflicts of interest, financial or otherwise.

Acknowledgment The authors would like to thank Ashley Hervey, MEd, for assistance with this manuscript.

The number of children diagnosed as overweight has more than doubled in recent years.1 More than one out of three pediatric and adolescent patients seen in the family medicine or pediatric settings are overweight.1 Overweight 5-year-olds are estimated to be four times more likely to become overweight or obese in adulthood when compared with children of healthy weight.2 Literature suggests clinicians are not consistently assessing body mass index (BMI) in children. Clinicians often use visual cues, which may lead to inaccurate assessment of BMI.3,4 This becomes problematic as clinicians have a tendency to underestimate weight when relying solely on visual cues for their assessment.4-6

The inability to accurately identify overweight or obesity in children may prolong proper diagnosis, placing them at an increased risk for developing comorbidities.3,7 In primary care, the US Preventive Services Task Force recommends clinicians screen for obesity beginning when patients are age 6 years.8 However, earlier identification of overweight status has been found to lead to improved management of obesity.3,9 Waiting until age 6 years may delay timely identification, diagnosis, and treatment of children who are considered overweight or obese. In emergency care, appropriate measurements (use of visual estimations or estimation tools) are necessary for appropriate medication dosing and to prevent underresuscitation.10 However, the use of a measurement tool such as the Broselow tape has been demonstrated as unreliable.11 As a result, clinicians use their own weight estimations, which are even less reliable than the Broselow tape, except in obese children.12,13 In a study specifically targeting children ages 3 to 5 years, a survey of physicians, resident physicians, and fourth-year medical students determined respondents were only able to accurately identify a patient as being obese 15% of the time and only slightly more likely to properly identify an overweight child (21%) with visual cues.4

Literature about the physician assistant (PA) workforce suggests a decreasing trend in primary care and expansion into subspecialties such as emergency medicine and trauma.14-16 In either practice, PAs will encounter overweight children. Evaluation of visual estimations of BMI in children ages 3 to 5 years has not been conducted with PAs or PA students. This study evaluated PA students' and recent PA graduates' ability to accurately assess BMI in patients ages 3 to 5 years, specifically:

  • How accurate are PA students and recent graduates in assessing BMI in patients ages 3 to 5 years using visual observation alone? With height and weight data?
  • Are there differences in the accuracy of PA students' and recent graduates' assessment of BMI based on their standing in the PA education program, confidence in their ability to predict BMI, experience with pediatric patients, or training with BMI-for-age growth charts?
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This was a cross-sectional survey of PA students (year 1 and year 2) and recent PA graduates of Wichita State University. Institutional Review Board approval was obtained. A link to the survey (Qualtrics Survey Software) was e-mailed to 140 eligible participants. A reminder was e-mailed 2 weeks after the initial e-mail to nonrespondents. Ninety-eight responses were received, for a response rate of 70%. Informed consent was implied by survey response.

The survey consisted of pictures (deidentified with pseudonyms) of 3- to 5-year-old children (Figure 1) and their height and weight information, used with permission from the CDC Internet-based training on using the BMI-for-age growth charts.17 Additional survey questions included self-reported confidence in ability to identify a child's BMI-for-age category accurately; beliefs regarding the importance of BMI-for-age category on a child's health; areas of the body (head/neck region, trunk/abdomen, arms/legs, or all regions) most important for obtaining an accurate assessment of their patient's BMI-for-age status; and demographics.



The respondents were first requested to describe each child's BMI for age through visual cues alone and categorize each into one of the following BMI categories: underweight (less than 5th percentile), healthy weight (5th to less than 85th percentile), overweight (85th to less than 95th percentile), and obese (greater than or equal to 95th percentile). Next, respondents were presented with the same photos, but also provided height and weight measurements for each child and asked to categorize them in the BMI groups. Respondents were requested to not to use any assistive devices or notes during this assessment.

Data analysis for this study was completed utilizing the Statistical Package for the Social Sciences (SPSS) version 20. Data were described through descriptive techniques, frequency reporting, and chi-square testing for nonparametric data analyses. The statistical significance for this study was set at a value of P≤.05.

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Respondent demographics are shown in Table 1. Respondents were mostly women (70.4%), non-Hispanic white (95.9%), and ranged in age from 22 to 44 years (mean=27.02; SD=4.29). Nearly 29% of respondents were first-year PA students, nearly 40% were second-year students, and nearly 32% were recent graduates.



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Primary outcomes—visual assessment results

Results without and with height and weight data are shown in Table 2. All survey respondents underestimated Child 1 (Mike, obese), based on visual assessment alone. There was a statistically significant (10 percentage points; P=.003) improvement when height and weight data were provided although most (89.8%) respondents still underestimated BMI. Most (81.6%) respondents appropriately categorized Child 2 (Mindy, healthy weight child). When height and weight data were provided, respondents' accuracy dropped from 81.6% to 54.1%, a statistically significant decline (33.7%; 27.5 percentage points; P<.001). Almost all (93.9%) underestimated Child 3 (Lisa, overweight). A statistically significant (150.8%; 9.2 percentage points; P=.038) improvement in categorization occurred when height and weight data were provided (15.3%, up from 6.1% correct).



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Secondary outcomes—comparisons between groups

Respondents' self-reported program standing, self-confidence, pediatric experience, and training with BMI-for-age growth chart are listed in Table 1. Accuracy by year in PA program is shown in Table 3; no significant differences between groups were found for any child with or without height and weight data (P values ranged from .112 to .889). Half of respondents (55.1%) reported assessing all body regions for estimating BMI. No statistically significant differences were found in categorization accuracy for any child with or without height and weight data (P values ranged from .227 to .864). In regard to self-reported confidence in ability to accurately categorize BMI for age in children, 26.5% of respondents reported being very confident (2%) or confident (24.5%); however, no statistically significant differences were found in categorization accuracy for any child with or without height and weight data by self-reported confidence (P values ranged from .226 to .742). About 40% of respondents reported previous pediatric experience; however, no statistically significant differences were found between those who did and did not report previous pediatric experience (P values ranged from .307 to 1) for any child with or without height and weight data. Half (50%) of the respondents reported having received training to use BMI-for-age growth charts; however, no statistically significant differences were found between training groups in accuracy with or without height and weight data (P values ranged from .435 to 1).



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This study evaluated PA students' and recent graduates' ability to accurately assess BMI in patients ages 3 to 5 years based solely on visual cues, followed by the addition of height and weight data. Further, group comparisons were completed to determine if there were differences based on self-reported program standing, confidence, previous pediatric experience, and previous training with BMI-for-age growth charts. Visual assessment alone was unreliable for all the respondents but especially in regard to Child 1 (Mike, obese) and Child 3 (Lisa, overweight) who were most often underestimated. This was consistent with findings from physicians, residents, and medical students using the same methodology as well as other studies.4-6,18 According to the literature, these underestimations may be a result of inappropriate perceptions of healthy weight status.19

Notable differences were found when comparing respondents' categorization responses with visual assessment (without height and weight data) and when height and weight data were provided. In the case of Child 1 (Mike, obese), initial visual assessments all were underestimated and a small improvement occurred with the addition of height and weight data. This is similar to the responses to Child 3 (Lisa, overweight), who was most often underestimated with visual assessment alone; an improvement was noted following the addition of height and weight data. However, in the case of Child 2 (Mindy, healthy weight), initial visual assessment alone was mostly correct with underestimation more often occurring when height and weight data were provided.

The data revealed no statistically significant improvements in categorization based on personal characteristics such as standing in the PA program, previous experience with pediatric patients, or training on the BMI-for-age growth chart. Although familiarity with pediatric patients or growth chart training might be expected to contribute to a clinician's ability to provide an accurate BMI assessment, this study revealed that previous experience does not improve accuracy of BMI-for-age categorization when using visual cues. Also, respondents who reported self-confidence in their ability to assess BMI performed no better than those who reported being somewhat confident or not confident at all.

Appropriate evaluation of BMI in young children (ages 3 to 5 years) is important in primary care, where early prevention for obesity may be delayed if not overweight is recognized. Annual calculation of BMI for children and adolescents is clearly recommended by the American Academy of Pediatrics as part of routine preventive healthcare.20 Despite recommendations, there is evidence that BMI calculations are not consistently being used in primary care.21,22 Qualitative research indicates that pediatric primary care providers more often watch trends using growth charts, as well as visual estimation, waiting to use BMI calculation until there is a concern.23 BMI use has been shown more effective when the parameter is automatically calculated in electronic health records.23,24 Pediatric providers should give priority to evaluating BMI during preventive care visits due to early risk for comorbidities such as diabetes, hypertension, and underlying endocrine disorders as well as social stigma. Correctly classifying children's BMI also is important in emergency care, especially as EDs often are used as a substitute for primary care and may need to provide routine preventive guidance.25 The concern about visual estimation alone is that in emergent situations, the urgency of patient care may preclude measuring the patient's height and weight. The evidence that providers more often underestimate pediatric BMI leads to the potential for seriously ill or injured children to be undertreated in weight-based treatments such as medication dosing or fluid resuscitation.10

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Potential limitations of this study include the use of black-and-white digital photographs as opposed to color photographs, video, or live children, and use of photographs depicting nonethnic, white children; providers may make more accurate assessments in live patient encounters. This study was conducted in a single PA education program and is not generalizable to all PAs. Previous pediatric experience was self-reported without specific guidelines. Survey distribution by e-mail may have limited the number of respondents; however, e-mail was chosen due to cost-effectiveness, ease of distribution, and resulting in fewer unanswered survey questions.26

Future research should include more experienced PAs but, more importantly, should evaluate how the knowledge of unreliable visual BMI estimations affects clinicians in their reliance on visual assessment or measurement tools. Research confirming these findings could assess PAs' ability to estimate BMI using standardized patients or patient videos. Further, research for visual estimation of BMI should evaluate various body regions as predictors for correct estimation.

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This study supports the body of literature that clinicians should not rely solely on visual assessment for categorizing BMI in children. PA students and recent PA graduates performed similarly to other medical professionals in the underestimation of BMI categorization of young children. This could be detrimental in pediatric patient care, both in early intervention in primary care for obesity and undertreatment in time-dependent urgent care. Instead, clinicians should consistently use height and weight measurements to document BMI in patients, basing their counseling and intervention on these measurements.

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body mass index; pediatric; obesity; physician assistant; PA; visual assessment

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