Estimating the Impact of Tuberculosis Case Detection in Constrained Health Systems: An Example of Case-Finding in South Africa.

Mathematical models are increasingly being used to compare strategies for tuberculosis (TB) control and inform policy decisions. Models often do not consider financial and other constraints on implementation and may overestimate the impact that can be achieved. We developed a pragmatic approach for incorporating resource constraints into mathematical models of TB. Using a TB transmission model calibrated for South Africa, we estimated the epidemiologic impact and resource requirements (financial, human resource (HR), and diagnostic) of 9 case-finding interventions. We compared the model-estimated resources with scenarios of future resource availability and estimated the impact of interventions under these constraints. Without constraints, symptom screening in public health clinics and among persons receiving care for human immunodeficiency virus infection was predicted to lead to larger reductions in TB incidence (9.5% (2.5th-97.5th percentile range (PR), 8.6-12.2) and 14.5% (2.5th-97.5th PR, 12.2-16.3), respectively) than improved adherence to diagnostic guidelines (2.7%; 2.5th-97.5th PR, 1.6-4.1). However, symptom screening required large increases in resources, exceeding future HR capacity. Even under our most optimistic HR scenario, the reduction in TB incidence from clinic symptom screening was 0.2%-0.9%-less than that of improved adherence to diagnostic guidelines. Ignoring resource constraints may result in incorrect conclusions about an intervention's impact and may lead to suboptimal policy decisions. Models used for decision-making should consider resource constraints.

Tracheobronchial calcifications in children.

BACKGROUND: Tracheobronchial calcifications are considered a rare radiologic finding in children. Our clinical experience indicates that this finding is not infrequently seen among children with prosthetic heart valves who have been treated with warfarin sodium. OBJECTIVE: We hypothesized that calcifications of the tracheobronchial tree are more common than previously reported in this patient population. MATERIALS AND METHODS: We reviewed the medical records and imaging studies of children who underwent cardiac valve replacement at our institution to estimate the prevalence. RESULTS: Tracheobronchial calcifications were identified on chest radiographs in 6 out of 17 children (35%), indicating that this imaging finding might be frequently overlooked. CONCLUSION: All children positive for tracheobronchial calcifications had been anticoagulated with warfarin sodium between the time of surgery and development of positive imaging findings. Our findings suggest that tracheobronchial calcifications are not uncommon in children treated with warfarin. Further investigation is necessary to determine wether there is a cause-effect relationship in these children.

CT findings and temporal course of persistent pulmonary interstitial emphysema in neonates: a multiinstitutional study.

OBJECTIVE: The purpose of this study was to evaluate the CT appearance, management, and temporal course of persistent pulmonary interstitial emphysema in neonates. MATERIALS AND METHODS: Criteria for inclusion in the study group included neonates with a history of prematurity who required ventilation for lung disease, development of hyperexpanded radiolucent lung lesions after typical radiographic findings of pulmonary interstitial emphysema, and CT documentation of lung abnormalities. Radiographs and CT scans were reviewed for the anatomic distribution, appearance, and presence of classic lines or dots within a radiolucent mass. We compared the management (surgical vs nonsurgical) and the temporal course in nonsurgical cases for patients in the United States and patients outside the United States. RESULTS: From seven institutions, we identified 17 patients who had persistent pulmonary interstitial emphysema with CT documentation. On CT, all lesions consisted of hyperexpanded cystic radiolucencies. Distribution was single-lobe in nine patients (left upper lobe, n = 5; left lower lobe, n = 3; right middle lobe, n = 1), multilobar in eight patients, and bilateral in six patients. Fourteen patients (82%) showed the characteristic line-and-dot pattern. All patients were initially treated conservatively; nine eventually underwent surgical resection with confirmation at pathology. Of 10 patients who underwent nonsurgical treatment for at least 1 year, lesions resolved in four patients, decreased in size in three asymptomatic patients, and enlarged in three patients, with eventual resection in two. Surgical resection was performed in 89% (8/9) of patients treated in the United States and in 13% (1/8) of patients treated outside the United States. CONCLUSION: Our study found that 82% of patients with persistent pulmonary interstitial emphysema had characteristic CT findings (central lines and dots surrounded by radiolucency). Although most patients in this series eventually underwent surgical resection, initial treatment can be conservative. The decision to perform surgery may have reflected the local medical culture.