

* Feinberg School of Medicine, Northwestern University, Chicago, Illinois
Division of Endocrinology
Mary Ann and J. Milburn Smith Child Health Research Program, Childrens Memorial Hospital, Chicago, Illinois
|| Infant Welfare Society of Chicago, Chicago, Illinois
| ABSTRACT |
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10 years of age who have a body mass index (BMI) of >85th percentile for age and at least 2 other risk factors (family history of type 2 diabetes, high-risk race/ethnicity, or evidence of insulin resistance, such as acanthosis nigricans). Objective. To describe the application of a type 2 diabetes mellitus screening protocol in an urban pediatric clinic.
Design/Methods. Medical records for patients 10 to 18 years of age who were examined in health maintenance visits during a 13-month period were reviewed; 997 subjects were included in the analyses. Data collected included demographic features, medical history, family history, physical examination findings, dietary and physical activity counseling, and results of laboratory tests. BMI percentiles for age were determined from national references.
Results. Subjects were 50% male (median age: 13.2 years), 96% Hispanic, and 48% (n = 477) had a >85th percentile BMI (including 26% with a
95th percentile BMI). Of the 477 subjects, 100% were in high-risk racial/ethnic groups, 29% had a family history of diabetes, and 20% demonstrated evidence of insulin resistance; 194 (41%) met the criteria for screening. Of those who met the criteria, 38% (n = 73) had screening ordered and 65 of those subjects (89%) completed screening. Acanthosis nigricans was more common among subjects for whom screening was ordered (69%), compared with subjects who were not screened (3%). Three screened subjects exhibited impaired glucose tolerance; none had overt diabetes. Subjects for whom screening was ordered were more likely to have received counseling than were subjects not recognized as qualifying for screening (84% vs 52%).
Conclusions. At this high-risk clinical site, the American Diabetes Association type 2 diabetes screening protocol was inconsistently applied. Acanthosis nigricans was a driving factor in identification and screening. Recognition of the need for screening was associated with a higher rate of documentation of nutritional counseling. Additional evaluation of the effectiveness of screening protocols in the early identification of diabetes and the effects of screening protocols on long-term morbidity is needed.
Key Words: child overweight type 2 diabetes screening primary care
Abbreviations: BMI, body mass index OW, overweight AROW, at risk for overweight ADA, American Diabetes Association OGTT, oral glucose tolerance test FPG, fasting plasma glucose PCOS, polycystic ovary syndrome IWS, Infant Welfare Society
Type 2 diabetes mellitus is a common disease among adults. According to recent estimates, 7.9% of US adults
18 years of age have diabetes, with type 2 diabetes representing 90% to 95% of cases.1 Until recently, type 2 diabetes was considered rare in the pediatric population, accounting for an estimated 2 to 3% of all newly diagnosed cases of childhood diabetes.2
Data from population- and clinic-based studies indicate an increasing prevalence of type 2 diabetes among children and adolescents.3 The prevalence of type 2 diabetes has increased 4- to 6-fold in 30 years among Pima Indian adolescents,4 a population that is known to be at high risk for the development of type 2 diabetes.5 A 10-fold increase in the incidence of type 2 diabetes among adolescents during a 12-year period was reported for a pediatric endocrinology clinic in Cincinnati, Ohio.2
Diabetes is associated with significant morbidity and premature death. Because the severity of complications of diabetes is linked to duration, onset at an early age likely portends increasing health problems among affected adults. Screening for diabetes may lead to diagnosis at an asymptomatic stage, thus decreasing complications. In 2000, the American Diabetes Association (ADA) issued recommendations for screening children for type 2 diabetes.6 The ADA criteria recommend testing children of
10 years of age who are overweight (OW) (defined as body mass index [BMI] of
95th percentile for age and gender) or at risk for OW (AROW) (defined as BMI of >85th percentile for age and gender, weight for height of >85th percentile, or weight >120% of ideal weight for height) and have at least 2 other risk factors. The risk factors include a family history of type 2 diabetes in a first- or second-degree relative, belonging to certain racial/ethnic groups (American Indian, African American, Hispanic, or Asian/Pacific Islander), or demonstrating evidence of insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, or polycystic ovary syndrome [PCOS]). The recommended screening test is fasting plasma glucose (FPG) measurement. In their statement, the ADA recognized that their recommendations were based on limited data and that additional studies are needed to demonstrate the value of individual screening tests and to establish the strength and risk level of various factors that might be influential in the development of type 2 diabetes. To date, there have been no published evaluations of the screening protocol with respect to its application or outcomes.
This study was designed to describe the application of the type 2 diabetes screening protocol in a high-risk population in a primary care practice setting. Outcome measures included the efficiency with which at-risk children were identified and provided with recommended laboratory testing and counseling services.
| METHODS |
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A retrospective medical record review was conducted for patients 10 through 18 years of age who were examined in a health maintenance visit during the 13-month period from February 2001 through February 2002. Computer-generated lists of appropriate-age patients examined each month during the study period were used to identify potential records for review. Visits were excluded if they were duplicates or a second visit for a subject, if the visit was not a routine health maintenance visit, or if height or weight was not recorded at the visit. A total of 1942 visits were on the computer-generated lists, and 1516 records (78%) were reviewed. Among the reviewed records, a total of 997 visits for 997 subjects met the criteria and were included in the analysis. This study was approved by the institutional review board of Childrens Memorial Hospital.
Medical Record Review
The data abstracted from each record included patient demographic features (age, gender, and racial/ethnic group), medical history (including a history of dyslipidemia or PCOS), family history of diabetes, physical examination findings (including height, weight, blood pressure, and the presence of acanthosis nigricans), growth interpretation (BMI calculation and plotting), counseling provided (diet and physical activity), and whether screening was recommended. It was standard practice at the clinic to include the Centers for Disease Control and Prevention 2000 growth charts in each record. Each medical record had a "problem list" section in the front, and each health maintenance visit form had a section titled "visit diagnoses." Diagnoses in these sections, including obesity, OW, or AROW, were considered positive indications of the recognition of OW. If screening for diabetes had been performed, then the results of screening were also determined.
Analyses
For each subject, the BMI percentile for age and gender was determined by using computer software based on the Centers for Disease Control and Prevention 2000 national growth reference.7 Interpretation of systolic blood pressure percentile for age and gender was determined on the basis of data from the 1996 National High Blood Pressure Education Program Working Group.8 The definition of hypertension we used for screening was a systolic blood pressure of
95th percentile for age. Subjects were considered to have PCOS or dyslipidemia if there was mention of either of these diagnoses in the problem list or visit diagnoses sections of the medical record. Impaired FPG was defined as a FPG level of 110 to 125 mg/dL, and impaired glucose tolerance was defined as a 2-hour glucose level from an OGTT of 140 to 199 mg/dL. Diabetes was defined as a FPG level of
126 mg/dL or a 2-hour glucose level from an OGTT of
200 mg/dL.
Subjects were first grouped into 3 BMI percentile categories, ie, OW, defined as BMI of
95th percentile for age; AROW, defined as BMI of 85th to 94th percentile for age; or non-OW, defined as BMI of
85th percentile for age. For each subject, the number of risk factors defined by the protocol (family history of diabetes, high-risk racial/ethnic group, or evidence of insulin resistance) was determined. Data were analyzed by using
2 and Fishers exact tests and the Mantel-Haenszel
2 test to examine trends, as appropriate. Analyses were conduced by using SPSS, version 11.0 (SPSS, Inc, Chicago, IL). Significance was set at P < .05.
| RESULTS |
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Prevalence of OW and Risk Factors for Type 2 Diabetes
The distribution of BMI percentiles for the study population is presented in Figure 1. Approximately one-half of the study population was either OW (26%) or AROW (22%). Therefore, 48% (477 of 997 subjects) met BMI criteria for screening. Associations of BMI groups with gender and age groups are presented in Table 1. Younger children and boys were more likely to be OW.
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Among the 57 subjects who met elevated systolic blood pressure criteria, only 7 (12%) were recognized as such in the visit diagnoses section of the medical record. Three other subjects (without systolic blood pressure elevation) had documentation of concerns regarding their blood pressure at the visit.
Documentation of counseling related to diet, fluid intake, television viewing, and physical activity was most likely to be provided for the OW subjects (Table 3). Overall, counseling or referral to a dietitian was documented in the record for 22% of non-OW subjects, 36% of AROW subjects, and 67% of OW subjects (P < .001). There was a strong association between diagnosis of OW at the visit and the provision of counseling. Counseling was documented for a majority (75%) of children with recognized OW, compared with 32% of children for whom OW status was not recognized (P < .001).
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Among the screening tests ordered for subjects who met the criteria for screening, 34 (47%) were FPG measurements and 39 (53%) were OGTTs. Both tests were scheduled in the morning after an 8-hour fast. Eighty-nine percent of subjects (65 of 73 subjects) with tests ordered completed their testing, with 4 subjects in each testing group failing to return. Although the OGTT was supposed to include both a FPG measurement and a glucose measurement 2 hours after glucose loading, 2 of the subjects who underwent an OGTT did not undergo FPG measurements. Therefore, there were 63 FPG and 35 OGTT 2-hour values in the analysis.
None of the subjects screened with FPG measurements demonstrated an abnormal result. Three subjects who underwent OGTT screening demonstrated results in the abnormal range; these 3 all exhibited impaired glucose tolerance and normal FPG levels. The subjects with abnormal OGTT results all had
98th percentile BMI values. No case of diabetes was diagnosed.
We next examined factors that contributed to provider identification of the need for a screening test. Among the 194 subjects who met the criteria for screening, several characteristics were more commonly found among those with screening ordered, ie, acanthosis nigricans, younger age, and higher BMI percentile (Table 4). Acanthosis nigricans demonstrated a particularly strong association with screening, inasmuch as screening was ordered for 93% of subjects identified as having acanthosis nigricans. A family history of diabetes was not well recognized, and subjects with this characteristic were less likely to be screened than those without this characteristic (30% vs 70%). There was not a significant difference in identification of elevated blood pressure among subjects for whom screening tests were ordered versus those for whom tests were not ordered (21% vs 24%). Of the 29 subjects with elevated blood pressure who met the criteria for screening but were "missed," 6 had 2 other screening factors that should have driven the ordering of screening tests. Of the remaining 23 subjects, 3 had a diagnosis of hypertension at the visit and the other 20 had elevated blood pressure according to our definition but were not recognized as such by the medical provider. Although only 3 subjects (0.6%) who met the criteria for screening had a diagnosis of dyslipidemia, concurrent lipid panel assessments were ordered for 40% (29 of 73 subjects) of those for whom screening was ordered. For no OW subjects was a lipid panel assessment ordered independent of either a FPG measurement or an OGTT.
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1 of the areas assessed, compared with 52% of those who met the criteria but did not have screening ordered (P < .001) (Fig 3). Similarly, 84% of subjects (61 of 73 subjects) for whom screening was ordered were recognized as OW in the visit diagnoses section of the medical record, compared with 23% of subjects (28 of 121 subjects) who were not screened (P < .001).
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| DISCUSSION |
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1 of 5 subjects (19%) qualified for type 2 diabetes screening according to clinic guidelines. Subjects for whom screening was ordered were more likely to be younger, have
95th percentile BMI, and have acanthosis nigricans. Once ordered, screening tests were nearly always obtained. Three of the 39 subjects who underwent OGTTs demonstrated abnormal results; all FPG test results were in the normal range. Recognition of OW status was associated with ordering of a screening test and documentation of provision of counseling related to diet, physical activity, or television viewing or referral to a dietitian. The high prevalences of OW and AROW among study subjects agree with other published findings. Hispanic children living in the United States have the highest prevalence of OW, compared with other population subgroups.9,10 The prevalence of OW among study subjects (26%) was similar to the findings of the National Health and Nutrition Examination Survey, 1999 to 2000, for Mexican Americans (23.7% prevalence of OW among children 611 years of age and 23.4% prevalence among children 1219 years of age).11 In addition, our findings on the prevalences of OW and AROW were similar to those reported by Lacar et al12 (OW, 22%; AROW, 18%) for a sample of 4375 Mexican American adolescents. Lacar et al12 also found that the prevalence of OW was higher for male subjects. However, our results differ in that those authors found that the average BMI increased with age, whereas we observed a higher prevalence of OW among younger subjects.
BMI is the commonly accepted index for classifying adiposity among adults. Expert committees and advisory groups have recommended BMI percentile-for-age as the accepted measure for assessing OW among children and adolescents.13,14 BMI-for-age percentiles were included on the revised Centers for Disease Control and Prevention growth charts from 2000.15 The advantages to using BMI-for-age as a screening tool for OW are that it provides a reference for adolescents that was not available with the weight-for-height percentiles and, because it is consistent with the adult index, BMI can be used to track childhood OW continuously into adulthood. Despite these recommendations and the usefulness of BMI percentile as a component of screening, we found that BMI was rarely used in this clinical practice. BMI calculations were documented in the records for only 92 of 997 subjects (9%), and BMI percentiles were plotted for only a very small percentage (10 of 997 subjects, 1%). Barriers to the use of BMI in clinical practice could include a lack of time to calculate and plot BMI values or a lack of knowledge on the use of BMI.
Recognition of OW status was associated with higher rates of documentation related to provision of counseling and the ordering of tests for type 2 diabetes screening. Systems to rapidly interpret and document weight status within the context of a busy practice are needed. Although our study design was not sufficient to evaluate changes related to the application of the screening protocol, we suspect that the application of the protocol heightened awareness of OW and enhanced the delivery of related counseling.
We found that 19% of children and adolescents examined in the clinic met the criteria for screening. Screening 1 in 5 patients in the clinic translates into testing a large number of patients. Fagot-Campagna et al16 used data from National Health and Nutrition Examination Survey III to estimate the number of US adolescents who would qualify for testing according to the ADA screening recommendations. Those authors estimated that 10% of adolescents 12 to 19 years of age would meet the criteria for screening. This was likely an underestimation, because it did not include all of the risk factors in the ADA recommendations. At our site, the rate was approximately twice their estimate.
The goal of screening is to detect undiagnosed diabetes or impaired glucose tolerance ("prediabetes") and delay associated complications. However, of the 65 subjects screened in our study, only 3 (4%) demonstrated abnormal test results, with no cases of diabetes and 3 cases of impaired glucose tolerance. Because we did not conduct follow-up evaluations, we do not know whether these 3 subjects received any direct benefit from the screening process. The benefits of detecting impaired glucose tolerance lie in the opportunity for intervention, with the goal of preventing progression to diabetes. Among adults, changes in lifestyle have been demonstrated to be effective in preventing the progression to type 2 diabetes among high-risk patients with impaired glucose tolerance.17 Similar data do not exist for children and adolescents.
The question of which is the best test for screening in primary care settings remains unanswered. Laboratory measurement of plasma glucose concentrations is preferred over the use of portable meters in screening for diabetes, because of the imprecision of meters.18 Hemoglobin A1C assessment is a valuable tool for monitoring glycemia but is not currently recommended for screening for diabetes.18 The ADA screening guidelines state that FPG measurement and the 2-hour OGTT are both suitable for testing. However, FPG measurement is the preferred test because of its lower cost and greater convenience, although the OGTT may be more sensitive for diagnosing impaired glucose tolerance. Whether FPG assessment or an OGTT should be used for screening remains controversial. Sinha et al19 examined the prevalence of impaired glucose tolerance among 167 obese children and adolescents. They found that 25% of the 55 obese children and 21% of the 112 obese adolescents demonstrated impaired glucose tolerance; however, <0.08% of those subjects exhibited impaired FPG levels. Of the 4% of adolescents with diabetes, all demonstrated impaired FPG levels. This finding suggests that fasting hyperglycemia is indicative of a more advanced stage of clinical diabetes and that FPG assessment is a much less sensitive method for detecting impaired glucose tolerance or a risk for the development of diabetes. Our finding of normal FPG levels for the 3 subjects with impaired glucose tolerance supports these findings.
A recent report issued by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus20 recommended lowering the cutoff point defining impaired FPG levels from
110 mg/dL to
100 mg/dL. With lowering of the cutoff point for impaired FPG levels, it is thought that impaired FPG level findings would include a greater percentage of individuals who also have impaired glucose tolerance. The Committee noted, however, that even with an impaired FPG cutoff point of 100 mg/dL, there will be individuals who exhibit impaired FPG levels but not impaired glucose tolerance and vice versa. In our study, 4 subjects exhibited FPG levels of
100 mg/dL, meeting criteria for impaired glucose tolerance under the new recommendations. One of these values was the fasting level in an OGTT with a normal 2-hour glucose level; in the other 3 cases, only the FPG level was assessed. Interestingly, our 3 subjects with impaired glucose tolerance all demonstrated FPG levels of <100 mg/dL. The Committee concluded that "there is currently inadequate clinical evidence that either test [FPG or OGTT] is superior."20(p3165) Additional studies are needed to determine the cost-benefit ratios for the FPG versus OGTT in high-risk pediatric populations.
We observed a moderate level of compliance with the screening protocol. Of the patients who met the criteria for screening, 38% were identified and had screening tests ordered. There are several potential reasons to explain the modest screening rate. First, the protocol was fairly new, and providers might not have been accustomed to using it routinely. Second, there were low rates of weight status interpretation documented in the medical records. Recognition of OW status is the first important step in the protocol. Patients with a diagnosis of OW (indicating provider recognition) were more likely to have screening ordered. Because many providers were not calculating BMI values and even fewer were plotting them, the providers must have been using other criteria (likely visual appearance) to establish which patients were considered OW. Visual appearance is likely effective only at its extremes. However, we found that acanthosis nigricans provided a strong visual cue to prompt screening. Other risk factors (such as family history or hypertension) did not provide such a visual cue, and their presence did not lead to enhanced rates of screening.
Twenty of the 121 "missed screening" subjects were missed because of a lack of recognition of elevated blood pressure by the medical provider. Because we did not review subsequent visits, it is possible that the subjects with elevated blood pressure were screened at a subsequent visit if the elevated blood pressure was confirmed. Alternatively, the subjects might have had normal blood pressure in subsequent visits, thus not meeting the criteria for screening. Overall, there was a low rate of recognition of hypertension in this clinic, with only 12% of subjects with elevated blood pressure having documentation of such in their medical records. The most likely reason for this poor recognition is the lack of a quick method for identifying elevated blood pressure in a busy clinical practice. This clinic did not have charts or graphs to evaluate blood pressure percentiles readily available for the medical providers; these could be added to the medical records or made available as a reference in the clinic. However, given the low rate of BMI plotting in this setting, an electronic linkage between the blood pressure cuff and a computerized system that provides age-based interpretation might be a preferable option.
A limitation of our study was the accuracy of our inclusion criteria for dyslipidemia. We based findings of dyslipidemia on recognition of the condition at the time of the visit, and we limited our record reviews to information found in the family history, problem list, and current visit sections of the records. Lipid profile assessments were not performed routinely; therefore, our findings of dyslipidemia do not represent the prevalence of lipid abnormalities in this population. The study would have been improved if we had reviewed lipid levels from all prior visits for the subjects for whom they were measured.
Another limitation was the accuracy of the identification of hypertension. We based findings of hypertension on an elevated blood pressure reading at the 1 visit reviewed and information recorded on the problem list. For the accurate diagnosis of hypertension, the childrens blood pressure should have been evaluated at several visits.
The study examined care provided in a busy clinic setting in a large urban area. Our findings may represent an underestimation of risk, because they were based on risk factors that had been documented by the medical provider in the medical record. Our study involved only 1 site, with an almost entirely Hispanic population. Risk factors likely differ among other populations. Population-based studies of the application of the screening guidelines are needed. The benefits and cost-effectiveness of the screening protocol are unclear. Additional study is needed to examine the effectiveness of screening protocols in the early identification of diabetes and the prevention of long-term morbidity.
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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Reprint requests to (S.D.) University of Chicago Childrens Hospital, 5839 S Maryland Ave, MC 5053, Chicago, IL 60637-1470. E-mail: sdrobac{at}peds.bsd.uchicago.edu
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