Revised estimates of diagnostic test sensitivity and specificity in suspected biliary tract disease.

BACKGROUND: The purpose of this study was to estimate the sensitivity and specificity of diagnostic tests for gallstones and acute cholecystitis. METHODS: All English-language articles published from 1966 through 1992 about tests used in the diagnosis of biliary tract disease were identified through MEDLINE. From 1614 titles, 666 abstracts were examined and 322 articles were read to identify 61 articles with information about sensitivity and specificity. Application of exclusion criteria based on clinical and methodologic criteria left 30 articles for analysis. Cluster-sampling methods were adapted to obtain combined estimates of sensitivities and specificities. Adjustments were made to estimates that were biased because the gold standard was applied preferentially to patients with positive test results. RESULTS: Ultrasound has the best unadjusted sensitivity (0.97; 95% confidence interval, 0.95 to 0.99) and specificity (0.95; 95% confidence interval, 0.88 to 1.00) for evaluating patients with suspected gallstones. Adjusted values are 0.84 (0.76 to 0.92) and 0.99 (0.97 to 1.00), respectively. Adjusted and unadjusted results for oral cholecystogram were lower. Radionuclide scanning has the best sensitivity (0.97; 95% confidence interval, 0.96 to 0.98) and specificity (0.90; 95% confidence interval, 0.86 to 0.95) for evaluating patients with suspected acute cholecystitis; test performance is unaffected by delayed imaging. Unadjusted sensitivity and specificity of ultrasound in evaluating patients with suspected acute cholecystitis are 0.94 (0.92 to 0.96) and 0.78 (0.61 to 0.96); adjusted values are 0.88 (0.74 to 1.00) and 0.80 (0.62 to 0.98). CONCLUSIONS: Ultrasound is superior to oral cholecystogram for diagnosing cholelithiasis, and radionuclide scanning is the test of choice for acute cholecystitis. However, sensitivities and specificities are somewhat lower than commonly reported. We recommend estimates that are midway between the adjusted and unadjusted values.

Consequences of the delayed diagnosis of ataxia-telangiectasia.

OBJECTIVES: Ataxia-telangiectasia (AT) is a rare, autosomal recessive neurodegenerative disorder in which the diagnosis is obvious when ataxia and telangiectasia are both present. However, the diagnosis can be made upon the onset of ataxia and before the appearance of telangiectasia if confirmed by laboratory tests. Early diagnosis is important for genetic counseling, appropriate care, and avoidance of unnecessary tests. The purpose of this study is to identify factors responsible for delays in the diagnosis of AT. DESIGN: The records of all patients seen at the Ataxia-Telangiectasia Clinical Center from July 1, 1995 to April 1, 1997 were reviewed to determine age of onset of gait abnormality, recognition of telangiectasia, and diagnosis. RESULTS: In 48 patients with AT, who were the index cases in their respective families, the median age of diagnosis (78 months) occurred after the onset of gait abnormalities (15 months) and closely corresponded to the development of telangiectasia (72 months). In the majority of cases (34/48), telangiectasia appeared before the diagnosis was established. The most common misdiagnosis was cerebral palsy (29/48 cases). Twenty-one children (4 with AT) were born after the start of symptoms in the index case, but before the establishment of a diagnosis. CONCLUSIONS: The term AT, although a concise and memorable label for the disorder, is also a barrier to early diagnosis. We recommend the use of routine serum alpha-fetoprotein testing for all children with persistent ataxia.

Reasons for pediatrician nonadherence to asthma guidelines.

BACKGROUND: The 1997 National Heart, Lung, and Blood Institute (NHLBI) asthma guidelines include recommendations on how to improve the quality of care for asthma. OBJECTIVE: To identify barriers to physician adherence to the NHLBI guidelines. DESIGN: Cross-sectional survey. PARTICIPANTS: A national random sample of 829 primary care pediatricians. MAIN OUTCOME MEASURES: Self-reported adherence to 4 components of the NHLBI guidelines (steroid prescription, instructing peak flow meter use, screening and counseling patients with asthma for smoking, and screening and counseling parents for smoking). We also collected information on physician demographics, practice characteristics, and possible barriers to adherence. We defined adherence as following a guideline component more than 90% of the time. RESULTS: The response rate was 55% (456/829). Most of the responding pediatricians were aware of the guidelines (88%) and reported having access to a copy of the guidelines (81%). Self-reported rates of adherence were between 39% and 53% for the guideline components. After controlling for demographics and other barriers, we found that nonadherence was associated with specific barriers for each guideline component: for corticosteroid prescription, lack of agreement (odds ratio [OR], 6.8; 95% confidence interval [CI], 3.2-14.4); for peak flow meter use, lack of self-efficacy (OR, 3.4; 95% CI, 1.9-6.1) and lack of outcome expectancy (OR, 4.7; 95% CI, 2.5-8.9); and for screening and counseling of patients and parents for smoking, lack of self-efficacy (OR, 3.8; 95% CI, 1.7-6.2 and OR, 2.8; 95% CI, 1.3-5.9, respectively). CONCLUSIONS: Although pediatricians in this sample were aware of the NHLBI guidelines, a variety of barriers precluded their successful use. To improve NHLBI guideline adherence, tailored interventions that address the barriers characteristic of a given guideline component need to be implemented.

Hepatitis B vaccination practices in hospital newborn nurseries before and after changes in vaccination recommendations.

BACKGROUND: Routine use of hepatitis B vaccine for low-risk newborns was suspended on July 7, 1999, because of concern about the potential risk of thimerosal, a mercury-containing vaccine preservative. Reinstatement of the birth dose was recommended when a thimerosal-free vaccine became available. OBJECTIVE: To explore changes in hepatitis B vaccination practices for newborns related to the revised recommendations for low-risk infants (in this study, the terms newborn and infant are used interchangeably). DESIGN: A telephone survey of a random sample of 1000 US hospitals. PARTICIPANTS: Nurse managers, nursery directors, and staff nurses of the newborn nurseries. MAIN OUTCOME MEASURES: Nursery vaccination practices before and after July 7, 1999, and the availability and use of thimerosal-free vaccine. RESULTS: Interviews were conducted with 773 (87%) of 886 eligible hospitals. Before July 7, 1999, 78% of the hospitals reported vaccination practices that were consistent with recommendations at that time, although only 47% vaccinated all low-risk infants at birth. After July 7, 1999, almost all hospitals discontinued vaccination of low-risk infants, in accordance with the recommendation change; however, there was a 6-fold increase in the number of hospitals that were not vaccinating all high-risk infants. After the introduction of thimerosal-free vaccine, only 39% of the hospitals reported vaccinating all low-risk infants. CONCLUSIONS: Most hospital nurseries altered their newborn hepatitis B vaccination practices consistent with changes in national recommendations. However, unintended consequences included the failure of some hospitals to continue vaccinating all high-risk infants and the delay in reintroducing vaccination for low-risk newborns after the introduction of a thimerosal-free vaccine. Assessments of the appropriateness of this country's response to the threat of thimerosal in vaccines should consider these findings.

Barriers pediatricians face when using asthma practice guidelines.

OBJECTIVE: To describe barriers to the successful use of the 1997 National Heart, Lung, and Blood Institute (NHLBI) asthma guidelines. METHODS: We conducted 3 focus groups to understand barriers to the use of 4 recommendations within the NHLBI guidelines (prescription of inhaled corticosteroids, recommendation of daily peak flowmeter use, smoking cessation screening and counseling, and allergen exposure counseling). PARTICIPANTS: Twenty-one pediatricians and 1 nurse practitioner, who each followed an average of 47 patients with asthma, participated. Six participants (27%) had a faculty or adjunct appointment at a medical school. Nineteen (90%) of the 21 pediatricians were board certified. RESULTS: We identified 171 comments about barriers to adherence. Type of recommendation and physician year of graduation from medical school were related to which barrier was prominent. For corticosteroid prescription, senior physicians mentioned lack of agreement, whereas younger physicians described lack of confidence in dosing or recognizing contraindications. For peak flow-meter use, senior physicians emphasized lack of training. Only senior physicians described the inertia of previous practice as a barrier. All groups mentioned time limitations. CONCLUSIONS: Efforts to improve adherence to asthma guidelines should consider the range of barriers that pediatricians face, such as lack of awareness, familiarity, or agreement, and external barriers owing to environmental, guideline, or patient factors. In addition, this study documents barriers not previously considered, such as lack of self-efficacy, lack of outcome expectancy, and inertia of previous practice, that prevent adherence. Because type of recommendation and physician demographics are related to which barriers are prominent, interventions to improve NHLBI guideline adherence should be tailored to these factors.

Morphine-augmented hepatobiliary scintigraphy: a meta-analysis.

The aim of this study was to compare the sensitivity and specificity of morphine-augmented hepatobiliary scintigraphy (MA-HBS) with that of conventional hepatobiliary scintigraphy (C-HBS) for acute cholecystitis. The results of most MA-HBS studies cannot be compared with C-HBS estimates, since articles describing C-HBS often include non-candidates for MA-HBS. However, using meta-analytic techniques to combine data from eligible studies (4 for C-HBS and 5 for MA-HBS), the specificity of MA-HBS (0.84; 95% CI = 0.75-0.94) was significantly greater (P = 0.008) than that of C-HBS (0.68; 95% CI = 0.61-0.75); there were no differences in sensitivity (MA-HBS; 0.96, 95% CI = 0.92-0.99; C-HBS: 0.97, 95% CI = 0.97-0.99).

Asymptomatic gallstones revisited. Is there a role for laparoscopic cholecystectomy?

OBJECTIVE: To compare the mortality effects of prophylactic laparoscopic cholecystectomy with that of expectant management in persons with asymptomatic gallstones. DESIGN: Decision analytic models of the two clinical strategies using input data from a review of the published medical literature pertaining to the epidemiology, natural history, and treatment outcomes related to gallstone disease. PATIENTS: Cohorts of men and women aged 30 and 50 years with asymptomatic gallstones. INTERVENTION: Prophylactic laparoscopic cholecystectomy performed at the time of diagnosis of asymptomatic gallstones or expectant management, defined as therapeutic intervention delayed until gallstone symptoms or complications spontaneously develop. MAIN OUTCOME MEASURES: Gallstone-related deaths and gallstone-related life-years lost for each age and gender cohort, by strategy. Models were subjected to rigorous sensitivity analysis to test the robustness of the results to changes in individual input variables. Outcomes were calculated with and without discounting nonfinancial benefits. RESULTS: The prophylactic laparoscopic cholecystectomy strategy led to fewer gallstone-related deaths than the expectant management strategy, but all of the deaths in the prophylactic laparoscopic cholecystectomy group occurred earlier in life. In cohorts older than age 30 years, the expectant management strategy resulted in fewer undiscounted gallstone life-years lost than the prophylactic laparoscopic cholecystectomy strategy. Discounting favored expectant management further because life-years lost were delayed compared with prophylactic surgery. Sensitivity analysis demonstrated the superiority of expectant management over a wide range of input assumptions. CONCLUSIONS: Prophylactic laparoscopic cholecystectomy should not be routinely recommended for individuals with asymptomatic gallstones.

Thymoma and cellular immune deficiency in an adolescent.

Thymoma has been associated with both humoral immunodeficiency and cellular immunodeficiency, but the latter association has never been described in the pediatric age group. We report a 15-year-old female with thymoma, recalcitrant oropharyngeal candidiasis, recurrent generalized cutaneous herpes simplex virus type 2 infection, recurrent pneumonia and myasthenia gravis. Pathology of the thymic lesion showed a 10x5x6 cm extensively hyalinized mass with residual regions of spindle cell predominant and lymphocyte-rich thymoma. There was no evidence of humoral immunodeficiency but there was clinical and laboratory evidence of cellular immunodeficiency with cutaneous anergy and absence of T cell proliferation to Candida antigen. Six weeks after the thymoma was resected, she was no longer anergic and Candida proliferation was normal, although she continued to experience infections. This is the first reported pediatric patient with an association of cellular immunodeficiency with thymoma.

Why don't physicians follow clinical practice guidelines? A framework for improvement.

CONTEXT: Despite wide promulgation, clinical practice guidelines have had limited effect on changing physician behavior. Little is known about the process and factors involved in changing physician practices in response to guidelines. OBJECTIVE: To review barriers to physician adherence to clinical practice guidelines. DATA SOURCES: We searched the MEDLINE, Educational Resources Information Center (ERIC), and HealthSTAR databases (January 1966 to January 1998); bibliographies; textbooks on health behavior or public health; and references supplied by experts to find English-language article titles that describe barriers to guideline adherence. STUDY SELECTION: Of 5658 articles initially identified, we selected 76 published studies describing at least 1 barrier to adherence to clinical practice guidelines, practice parameters, clinical policies, or national consensus statements. One investigator screened titles to identify candidate articles, then 2 investigators independently reviewed the texts to exclude articles that did not match the criteria. Differences were resolved by consensus with a third investigator. DATA EXTRACTION: Two investigators organized barriers to adherence into a framework according to their effect on physician knowledge, attitudes, or behavior. This organization was validated by 3 additional investigators. DATA SYNTHESIS: The 76 articles included 120 different surveys investigating 293 potential barriers to physician guideline adherence, including awareness (n = 46), familiarity(n = 31), agreement (n = 33), self-efficacy (n = 19), outcome expectancy (n = 8), ability to overcome the inertia of previous practice (n = 14), and absence of external barriers to perform recommendations (n = 34). The majority of surveys (70 [58%] of 120) examined only 1 type of barrier. CONCLUSIONS: Studies on improving physician guideline adherence may not be generalizable, since barriers in one setting may not be present in another. Our review offers a differential diagnosis for why physicians do not follow practice guidelines, as well as a rational approach toward improving guideline adherence and a framework for future research.

Predictors of common bile duct stones prior to cholecystectomy: a meta-analysis.

BACKGROUND: The decision of whether or not to investigate for common bile duct stones before cholecystectomy utilizes clinical, laboratory, and radiologic information (indicators). There is tremendous individual variation among clinicians in the criteria used for making this decision. Our aim was to perform a meta-analysis of published data to estimate the performance characteristics of the most commonly used preoperative indicators of common bile duct stones. METHODS: Using predetermined exclusion criteria, we selected articles from a MEDLINE search and bibliographic review. Weighted averages were used to determine summary sensitivity, specificity, and positive and negative likelihood ratios for each indicator for stones. RESULTS: From 2221 citations identified, 22 studies met inclusion criteria. The 10 indicators examined were reported in a common fashion in three or more articles, and could be assessed preoperatively. Seven exhibited a specificity greater than 90%. Indicators with positive likelihood ratios of 10 or above were cholangitis, preoperative jaundice, and ultrasound evidence of common bile duct stones. Positive likelihood ratios for dilated common bile duct on ultrasound, hyperbilirubinemia, and jaundice ranged from almost 4 to almost 7. Elevated levels of alkaline phosphatase, pancreatitis, cholecystitis, and hyperamylasemia exhibited positive likelihood ratios of less than 3. CONCLUSIONS: This meta-analysis has identified indicators for duct stones and ranked them according to likelihood ratios. These findings can be applied as guidelines for whether to investigate for duct stones before cholecystectomy.