Biomedical subjects

Michael R Kosorok

Publications and source records attributed to Michael R Kosorok.

At least 19 recordsLinked to original sources

PubMed2006

Reproducibility of a scoring system for computed tomography scanning in cystic fibrosis.

INTRODUCTION: Computerized tomography (CT) scanning shows promise as an outcome surrogate for cystic fibrosis (CF) lung disease progression. The scoring system used to convert the CT image to numeric data is an essential determinant of the performance of CT scanning. METHODS: Three radiologists independently scored 16 high-resolution CT scans performed on children in the Wisconsin CF Neonatal Screening Project. The test scans were selected to provide a broad range of disease severity. The scoring system provided subscores for the presence and severity of 5 findings of CF lung disease. The sum of the subscores provided a total score. The CT scans were then read again by each of the radiologists at least 11 months later. Using Mixed Effects Linear Model Analysis, the sources of error (scan-to-scan variation, interrater variance, and intrarater variance) were calculated. RESULTS: For the total score, the scan-to-scan variation was 14.48, interrater variance was 0.28, and intrarater variance was 0.45, with an overall reproducibility of 95%. The square root of scan-to-scan variance, a measure of sensitivity, was 3.81. Evaluation of the subscores showed higher reproducibility for bronchiectasis and hyperinflation (95% and 88%, respectively). The bronchiectasis score was more sensitive than the air-trapping score (1.46 vs. 0.89). DISCUSSION: This system was developed to provide a reproducible method that could be used to evaluate the lobar location, severity, and extent of a broad spectrum of CT features of CF lung disease, especially in children. This study demonstrates that the overall score is both sensitive to variation in the severity of lung disease and reproducible.

Adolescent↗

PubMed2006

Additive risk models for survival data with high-dimensional covariates.

As a useful alternative to Cox's proportional hazard model, the additive risk model assumes that the hazard function is the sum of the baseline hazard function and the regression function of covariates. This article is concerned with estimation and prediction for the additive risk models with right censored survival data, especially when the dimension of the covariates is comparable to or larger than the sample size. Principal component regression is proposed to give unique and numerically stable estimators. Asymptotic properties of the proposed estimators, component selection based on the weighted bootstrap, and model evaluation techniques are discussed. This approach is illustrated with analysis of the primary biliary cirrhosis clinical data and the diffuse large B-cell lymphoma genomic data. It is shown that this methodology is numerically stable and effective in dimension reduction, while still being able to provide satisfactory prediction and classification results.

Humans↗

PubMed2006

Robust semiparametric microarray normalization and significance analysis.

Microarray technology allows the monitoring of expression levels of thousands of genes simultaneously. A semiparametric location and scale model is proposed to model gene expression levels for normalization and significance analysis purposes. Robust estimation based on weighted least absolute deviation regression and significance analysis based on the weighted bootstrap are investigated. The proposed approach naturally combines normalization and significance analysis, and incorporates the variations due to normalization into the significance analysis properly. A small simulation study is used to compare finite sample performance of the proposed approach with alternatives. We also demonstrate the proposed method with a real dataset.

Biometry↗

PubMed2005

Cystic fibrosis mutations and genotype-pulmonary phenotype analysis.

BACKGROUND: Although there are more than 1000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, most of them are uncommon and only limited information exists regarding genotype-pulmonary phenotype relationships. METHODS: We determined and classified the CFTR mutations using denaturing high-performance liquid chromatography and developed new, quantitative methods to categorize pulmonary phenotypes. RESULTS: Two novel alleles were discovered, namely G1047R and 1525-2A-->G, which were accompanied by F508del and G551D mutations, respectively. Assessment of numerous options revealed that CF pulmonary phenotype categorization in children cannot be accomplished with clinical or pulmonary function data but is facilitated by longitudinal quantitative chest radiology. It was most useful to categorize pulmonary disease status by evaluating the typical pattern of abnormalities in patients homozygous for the F508del mutation, and then compare patients with minor mutations to this typical CF pulmonary phenotype. By this method, both patients with novel mutations have pulmonary phenotypes typical of F508del homozygotes. However, patients with class IV mutations (e.g., R347P) or with pancreatic sufficiency showed serial chest radiographs that were atypically mild. CONCLUSIONS: Longitudinal quantitative chest radiography provides a new strategy for CF pulmonary phenotype categorization that should be useful for genotype-phenotype delineation in individual patients and in both epidemiologic studies and clinical trials involving groups of children with CF.

Child↗

PubMed2005

Longitudinal development of mucoid Pseudomonas aeruginosa infection and lung disease progression in children with cystic fibrosis.

CONTEXT: Although Pseudomonas aeruginosa is the most common virulent respiratory pathogen in cystic fibrosis (CF), the longitudinal development of P aeruginosa infection and its effect on antibody responses and lung disease progression in children with CF remain unclear. OBJECTIVE: To prospectively examine the epidemiology of P aeruginosa infection and its impact on CF pulmonary morbidity. DESIGN, SETTING, AND PATIENTS: We prospectively evaluated 56 CF patients at 2 CF centers in Madison and Milwaukee, Wis, from birth up to age 16 years between April 15, 1985, and April 15, 2004, with diagnoses made through the Wisconsin CF Neonatal Screening Project. MAIN OUTCOME MEASURES: Timing of nonmucoid P aeruginosa and mucoid P aeruginosa acquisition was assessed by first positive result. Longitudinal development from no P aeruginosa to nonmucoid P aeruginosa and from nonmucoid P aeruginosa to mucoid P aeruginosa was examined. Outcome measurements included antibody titers, respiratory symptoms, quantitative chest radiography, and pulmonary function tests. RESULTS: Sixteen patients (29%) acquired nonmucoid P aeruginosa in the first 6 months of life. The age-specific prevalence of mucoid P aeruginosa increased markedly from age 4 to 16 years. Nonmucoid and mucoid P aeruginosa were acquired at median ages of 1.0 and 13.0 years, respectively. In contrast with the short transition time from no P aeruginosa to nonmucoid P aeruginosa, the transition time from nonmucoid to mucoid P aeruginosa was relatively long (median, 10.9 years) and could be slightly extended by brief/low anti-P aeruginosa antibiotic treatment. Antibody titers increased with both transitions, but the deterioration in cough scores, chest radiograph scores, and pulmonary function correlated best with transition from nonmucoid to mucoid P aeruginosa. CONCLUSIONS: Early prevention and detection of nonmucoid and mucoid P aeruginosa are critical because of early acquisition and prevalence. There is a window of opportunity for suppression and possible eradication (by aggressive anti-P aeruginosa treatment) of initial nonmucoid P aeruginosa. Mucoid P aeruginosa plays a much greater role in CF lung disease progression than nonmucoid P aeruginosa. Antibody titers, cough scores, and chest radiographs are early signs of nonmucoid P aeruginosa and especially mucoid P aeruginosa stages.

Adolescent↗

PubMed2005

Preventing early, prolonged vitamin E deficiency: an opportunity for better cognitive outcomes via early diagnosis through neonatal screening.

OBJECTIVE: To evaluate whether early diagnosis of cystic fibrosis (CF) through newborn screening (NBS) and early vitamin E status are associated with cognitive function. STUDY DESIGN: We assessed cognitive function for 71 children without meconium ileus (ages 7.3-16.9 years) enrolled in the screened (S) or control (C) group of the Wisconsin CF Neonatal Screening Project. The Test of Cognitive Skills, 2nd edition generated the cognitive skills index (CSI; mean = 100, SD = 16). Vitamin E deficiency at diagnosis was defined as plasma alpha-tocopherol (alpha-T) below 300 microg/dL (<300E). Primary analyses evaluated CSI scores across the 4 levels of group (S or C) by using alpha-T status (<300E or >300E) with analysis of covariance. RESULTS: After adjusting for covariates, CSI in the C<300E group was significantly lower than each of the other groups (C>300E, S<300E, and S>300E; P < .05). The highest proportion of CSI scores >84 occurred in the C<300E group (41%). Patients in this group also had the lowest mean head circumference z-scores at diagnosis. CONCLUSIONS: Our results show that prolonged alpha-T deficiency in infancy is associated with lower subsequent cognitive performance. Thus, diagnosis via NBS may benefit the cognitive development of children with CF, particularly in those prone to vitamin E deficiency during infancy.

Adolescent↗

PubMed2005

Evidence on improved outcomes with early diagnosis of cystic fibrosis through neonatal screening: enough is enough!

OBJECTIVE: To generate and examine evidence in support of diagnosing cystic fibrosis (CF) early through newborn screening (NBS). STUDY DESIGN: Using a randomized controlled trial with unique unblinding/surveillance, we evaluated patients with CF receiving similar treatment after assignment to an early diagnosis (screened) group or to a control group. Outcomes studied at diagnosis and longitudinally included measures of nutritional status and lung disease. RESULTS: Assessment of patients with CF without meconium ileus who had pancreatic insufficiency revealed marked differences in age and condition at diagnosis--screened patients had significantly better length/height, weight, and head circumference. Follow-up evaluation for 16 years showed that height and weight differences persisted long term. Although screened patients had better chest x-ray scores at diagnosis, our trial suggests that the effects of confounders such as Pseudomonas aeruginosa infections led to deterioration of their scores after 10 years, but there were no significant differences between the 2 CF/pancreatic insufficiency subgroups. CONCLUSIONS: Early diagnosis of CF and aggressive nutritional management can prevent malnutrition and growth failure. Although CF NBS provides a potential opportunity for better pulmonary outcomes, it appears that other factors can predominate over time in pulmonary prognosis. Overall, the Wisconsin trial is positive and provides enough evidence for routine CF NBS.

Age Factors↗

PubMed2005

A sample size formula for the supremum log-rank statistic.

An advantage of the supremum log-rank over the standard log-rank statistic is an increased sensitivity to a wider variety of stochastic ordering alternatives. In this article, we develop a formula for sample size computation for studies utilizing the supremum log-rank statistic. The idea is to base power on the proportional hazards alternative, so that the supremum log rank will have the same power as the standard log rank in the setting where the standard log rank is optimal. This results in a slight increase in sample size over that required for the standard log rank. For example, a 5.733% increase occurs for a two-sided test having type I error 0.05 and power 0.80. This slight increase in sample size is offset by the significant gains in power the supremum log-rank test achieves for a wide range of nonproportional hazards alternatives. A small simulation study is used for illustration. These results should facilitate the wider use of the supremum log-rank statistic in clinical trials.

Biometry↗

PubMed2005

A controlled, randomized, double-blind trial of prophylaxis against jaundice among breastfed newborns.

OBJECTIVES: Neonatal jaundice is a greater problem for infants fed breast milk, compared with formula. This study tested the hypotheses that feeding breastfed newborns beta-glucuronidase inhibitors during the first week after birth would increase fecal bilirubin excretion and would reduce jaundice without affecting breastfeeding deleteriously. METHODS: Sixty-four breastfed newborns were randomized to 4 groups, ie, control or receiving 6 doses per day (5 mL per dose) of L-aspartic acid, enzymatically hydrolyzed casein (EHC), or whey/casein (W/C) for the first week. L-aspartic acid and EHC inhibit beta-glucuronidase. Transcutaneous bilirubin levels (primary outcome) were measured daily (Jaundice Meter [Minolta/Air Shields, Hatboro, PA] and Bilicheck [Respironics, Pittsburgh, PA]). All stools were collected, and fecal bile pigments, including bilirubin diglucuronide, bilirubin monoglucuronides, and bilirubin, were analyzed with high-performance liquid chromatography. Follow-up assessments included day 7 body weight, day 6/7 prebreastfeeding/postbreastfeeding weights, maternal ratings, and ages at formula introduction and breastfeeding cessation. RESULTS: The groups were comparable at entry. Overall, the L-aspartic acid, EHC, and W/C groups had significantly lower transcutaneous bilirubin levels than did the control group (75.8%, 69.6%, and 69.2%, respectively, of the control mean, 8.53 mg/dL, at the bilirubin peak on day 4). The L-aspartic acid, EHC, and W/C groups had significantly lower transcutaneous bilirubin levels on days 3 to 7. Fecal bile pigment excretion was greatest in the L-aspartic acid group, significantly greater than control values. There were no significant differences in dosages, follow-up measurements, and maternal ratings. CONCLUSIONS: Use of minimal aliquots of L-aspartic acid and EHC for beta-glucuronidase inhibition results in increased fecal bilirubin excretion and less jaundice, without disruption of the breastfeeding experience. Decreased jaundice in the W/C group, which lacked a beta-glucuronidase inhibitor, suggests a different mechanism.

Aspartic Acid↗

PubMed2004

Association between initial disease presentation, lung disease outcomes, and survival in patients with cystic fibrosis.

This US study was conducted to determine whether mode of diagnosis and initial disease presentation influence lung disease and survival in patients with cystic fibrosis. The study population included 27,703 patients reported to the 1986-2000 Cystic Fibrosis Foundation Registry. Patients were segregated into four diagnostic categories: meconium ileus (MI), prenatal/neonatal screening (SCREEN), positive family history (FH), and symptoms other than meconium ileus (SYMPTOM). When compared with patients in the SCREEN group, those in the MI or SYMPTOM group were found to have significantly greater risks of shortened survival, Pseudomonas aeruginosa acquisition, and forced expiratory volume in 1 second (FEV(1)) below 70% of predicted. In the SYMPTOM group, the greatest risks of shortened survival, P. aeruginosa acquisition, and FEV(1) <70% occurred for patients presenting with combined respiratory and gastrointestinal symptoms, followed by respiratory or gastrointestinal symptoms alone; the best outcomes were in patients with other presenting features. Additionally, patients with presumably "severe" genotypes (DeltaF508 plus other class I, II, III mutations in both alleles) had greater risks of shortened survival and P. aeruginosa acquisition compared with patients with presumably "mild" genotypes (class IV or V mutations in one or both alleles).

Age of Onset↗

PubMed2004

Longitudinal pulmonary status of cystic fibrosis children with meconium ileus.

Although meconium ileus (MI) is the earliest manifestation of cystic fibrosis (CF), and is associated with poorer growth, the longitudinal pulmonary progression of CF children with MI is not clear. To test the hypothesis that MI is associated with worse pulmonary outcomes, we prospectively compared from diagnosis to 12 years of age 32 CF children with MI to 50 CF children without MI who were diagnosed during early infancy through neonatal screening. Pulmonary outcome measures included respiratory symptoms, respiratory infections, pathogens, antibiotic usage, hospitalizations, quantitative chest radiology, spirometry, and lung volume determinations. Obstructive lung disease was defined as percent predicted spirometry values below the lower limits of normal. Longitudinal analyses revealed no significant differences in cough, wheezing, respiratory infections, prevalence of and median times to acquisition of Pseudomonas aeruginosa or Staphylococcus aureus, antibiotic usage, and chest radiograph scores between the two groups. However, MI children showed significantly worse forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC), forced expiratory flow between 25-75% of FVC (FEF(25-75)), % predicted FEV(1), % predicted FEF(25-75), and total lung capacity (TLC). These differences were particularly apparent beginning at age 8-10 years. MI children also had higher rates of and shorter median times to obstructive lung disease. Subgroup analyses showed MI children treated surgically and those treated medically had similar pulmonary outcomes. In conclusion, MI children have worse lung function and more obstructive lung disease than those without MI. Such abnormalities are accompanied by reduced lung volume. MI is a distinct CF phenotype with more severe pulmonary dysfunction.

Airway Obstruction↗

PubMed2004

Design and analysis of group sequential clinical trials with multiple primary endpoints.

In many phase III clinical trials, it is desirable to separately assess the treatment effect on two or more primary endpoints. Consider the MERIT-HF study, where two endpoints of primary interest were time to death and the earliest of time to first hospitalization or death (The International Steering Committee on Behalf of the MERIT-HF Study Group, 1997, American Journal of Cardiology 80[9B], 54J-58J). It is possible that treatment has no effect on death but a beneficial effect on first hospitalization time, or it has a detrimental effect on death but no effect on hospitalization. A good clinical trial design should permit early stopping as soon as the treatment effect on both endpoints becomes clear. Previous work in this area has not resolved how to stop the study early when one or more endpoints have no treatment effect or how to assess and control the many possible error rates for concluding wrong hypotheses. In this article, we develop a general methodology for group sequential clinical trials with multiple primary endpoints. This method uses a global alpha-spending function to control the overall type I error and a multiple decision rule to control error rates for concluding wrong alternative hypotheses. The method is demonstrated with two simulated examples based on the MERIT-HF study.

Adrenergic beta-Antagonists↗

PubMed2004

Cognitive function of children with cystic fibrosis: deleterious effect of early malnutrition.

OBJECTIVE: Patients who have cystic fibrosis (CF) and experience delayed diagnosis by traditional methods have greater nutritional insult compared with peers diagnosed via neonatal screening. The objective of this study was to evaluate cognitive function in children with CF and the influence of both early diagnosis through neonatal screening and the potential effect of early malnutrition. METHODS: Cognitive assessment data were obtained for 89 CF patients (aged 7.3-17 years) during routine clinic visits. Patients had been enrolled in either the screened (N = 42) or traditional diagnosis (control) group (N = 47) of the Wisconsin CF Neonatal Screening Project. The Test of Cognitive Skills, Second Edition was administered to generate the Cognitive Skills Index (CSI) and cognitive factor scores (Verbal, Nonverbal, and Memory). RESULTS: Cognitive scores in the overall study population were similar to normative data (CSI mean [standard deviation]: 102.5 [16.6]; 95% confidence interval: 99.1-105.9). The mean (standard deviation) CSI scores for the screened and control groups were 104.4 (14.4) and 99.8 (18.5), respectively. Significantly lower cognitive scores correlated with indicators of malnutrition and unfavorable family factors such as single parents, lower socioeconomic status, and less parental education. Our analyses revealed lower cognitive scores in patients with low plasma alpha-tocopherol (alpha-T) levels at diagnosis. In addition, patients in the control group who also had vitamin E deficiency at diagnosis (alpha-T < 300 microg/dl) showed significantly lower CSI scores in comparison with alpha-T-sufficient control subjects and both deficient and sufficient alpha-T subsets of screened patients. CONCLUSION: Results suggest that prevention of prolonged malnutrition by early diagnosis and nutritional therapy, particularly minimizing the duration of vitamin E deficiency, is associated with better cognitive functioning in children with CF.

Adolescent↗

PubMed2003

Bronchopulmonary disease in children with cystic fibrosis after early or delayed diagnosis.

Although early diagnosis of cystic fibrosis (CF) can lead to nutritional benefits, there has been uncertainty about pulmonary outcomes. Using a randomized controlled trial with unique unblinding/surveillance, we evaluated patients with CF who received similar treatment after being assigned to an early diagnosis (screened) group or to a standard diagnosis (control) group. When the youngest patient was 7 years of age, we compared outcomes using pulmonary function data and quantitative chest radiology. In the screened group (56 patients), diagnosis was made at a younger age of 12.4 weeks, compared with the diagnosis in control group (47 control patients) at the age of 95.8 weeks, but included a significantly greater proportion of patients with deltaF508 genotypes and pancreatic insufficiency. The first chest radiograph showed significantly fewer abnormalities in the screened group; but, over time, the two groups converged, and after 10 years of age the screened patients showed worse chest X-ray scores associated with earlier acquisition of Pseudomonas aeruginosa. No differences were detected in any measure of pulmonary dysfunction, which was generally mild in each group. Although CF neonatal screening provides a potential opportunity for better pulmonary outcomes, it appears that respiratory infections and pancreatic status are the dominant factors in pulmonary prognosis.

Adolescent↗

PubMed2003

Longitudinal evaluation of bronchopulmonary disease in children with cystic fibrosis.

Children with cystic fibrosis (CF) develop bronchopulmonary disease at variable ages. Determining the epidemiology of chronic lung disease and quantifying its severity, however, have been difficult in infants and young children. As part of the Wisconsin CF Neonatal Screening Project, we were presented with an ideal opportunity to assess longitudinally the evolution of symptoms, signs, and quantitative measures of CF respiratory disease. After newborn screening test results led to early recognition, 64 patients diagnosed at a median age of 6.71 weeks were enrolled and studied systematically at a median age of 11.3 years to obtain clinical information, chest radiographs, and pulmonary function tests. Our observations revealed that a frequent cough by history is evident by 10.5 months of age in half the patients. Quantitative chest radiology (CXR scoring) demonstrated that potentially irreversible abnormalities are present in half the children by 2 years. The severity of Wisconsin and Brasfield CXR scores increased in association with respiratory infections. Longitudinal progression of Wisconsin CXR scores was related to age (P < 0.001), pancreatic insufficiency (P = 0.005), and respiratory secretion cultures positive for Staphylococus aureas (P = 0.039). In contrast, serial spirometry showed limited sensitivity, as did lung volume determinations; neither was satisfactory as repeated measures with acceptable quality control until after 7 years of age. Time to event analyses revealed that half the patients had % predicted FEF(25-75) and FEV(1)/FVC values greater than 80% until 10.7 and 9.9 years, respectively. We conclude that of the methods evaluated, quantitative chest radiology is currently the best procedure for frequent assessment of bronchopulmonary disease in CF, and that radiographic progression is evident in approximately 85% of patients by 5 years of age. Our results also suggest that bronchiectasis and other radiographic evidence of chronic infection are apparent prior to airways obstruction in young CF patients.

Age of Onset↗

PubMed2003

Temper tantrums in young children: 2. Tantrum duration and temporal organization.

This article completes the analysis of parental narratives of tantrums had by 335 children aged 18 to 60 months. Modal tantrum durations were 0.5 to 1 minute; 75% of the tantrums lasted 5 minutes or less. If the child stamped or dropped to the floor in the first 30 seconds, the tantrum was likely to be shorter and the likelihood of parental intervention less. A novel analysis of behavior probabilities that permitted grouping of tantrums of different durations converged with our previous statistically independent results to yield a model of tantrums as the expression of two independent but partially overlapping emotional and behavioral processes: Anger and Distress. Anger rises quickly, has its peak at or near the beginning of the tantrum, and declines thereafter. Crying and comfort-seeking, components of Distress, slowly increase in probability across the tantrum. This model indicates that tantrums can provide a window on the intense emotional processes of childhood.

Anger↗

PubMed2002

Delayed diagnosis of US females with cystic fibrosis.

This study was conducted to examine a patient's age and condition at the time of diagnosis as one potential factor contributing to the "gender gap" in cystic fibrosis. The study population consisted of 11,275 US patients diagnosed during 1986-1998 and reported to the Cystic Fibrosis Foundation Registry in the same or the following calendar year. Parallel analyses were performed for Wisconsin patients identified prospectively during 1985-1994 to obtain more detailed information on their condition at diagnosis. Analyses of the registry data showed that females identified because of symptoms other than meconium ileus were diagnosed at significantly older ages (median, 12.7 months) than were males (median, 8.7 months) (p < 0.001). The delay in diagnosis for females was most evident among patients presenting with respiratory symptoms only (median, 40.7 vs. 22.3 months; p < 0.001). Analyses of Wisconsin patients demonstrated no significant gender differences in cough and wheezing experiences or in chest radiographic severity scores between males and females during their first 10 years of life, although a disproportionately high number of males were referred for diagnostic sweat testing. A delay in diagnosis of females with cystic fibrosis was discovered, suggesting either differential recognition of respiratory symptoms or a gender bias.

Age Distribution↗

PubMed2002

Respiratory infections with Pseudomonas aeruginosa in children with cystic fibrosis: early detection by serology and assessment of risk factors.

CONTEXT: Patients with cystic fibrosis (CF) are susceptible to lower respiratory tract infections with Pseudomonas aeruginosa and typically acquire this organism in early childhood. Once P aeruginosa infection is established, eradication may be impossible, and progressive lung disease often aggravates morbidity and mortality risks. The ability to diagnose CF by genetic testing at birth makes it possible to determine the temporal sequence of events that result in P aeruginosa-associated pulmonary infections. OBJECTIVE: To evaluate the longitudinal relationship between the production of an antibody response against P aeruginosa and clinical factors associated with P aeruginosa pulmonary infections in patients with CF diagnosed in early life. DESIGN, SETTING, AND PATIENTS: Serum samples and oropharyngeal cultures (protocol cultures) were obtained at 6-month intervals from April 15, 1985, to April 15, 2000 (or for up to 180 months depending on their enrollment date) from 68 patients at 2 centers in Madison and Milwaukee, Wis, diagnosed through the Wisconsin CF Neonatal Screening Project, a longitudinal cohort study. Additional cultures were obtained at examining physicians' discretion (all cultures). MAIN OUTCOME MEASURES: Time to serum IgG, IgA, and IgM antibody titer of at least 1:256 against P aeruginosa, assessed by enzyme-linked immunosorbent assay using cell lysate, exotoxin A, and elastase as antigens; time to organism isolation from respiratory samples; time to Wisconsin Cystic Fibrosis Radiograph (WCXR) score of 5 or more. RESULTS: The median time to an antibody titer of at least 1:256 was 17.8, 24.2, and 70.9 months for cell lysate, exotoxin A, and elastase, respectively. The rise of anti-cell lysate and anti-exotoxin A titers to 1:256 or more occurred a mean of 11.9 (P<.001) and 5.6 (P =.04) months, respectively, before the isolation of P aeruginosa for all cultures and 18.2 (P<.001) and 11.9 (P =.006) months, respectively, before protocol cultures. There was no significant difference between the rise of anti-cell lysate and anti-exotoxin A titer and a WCXR score of 5 or more (P =.24 and.32, respectively). Treatment with long-term, non-Pseudomonas oral antibiotics and integration of CF infants with older, chronically infected patients were associated with a significantly increased risk of P aeruginosa pulmonary infection. CONCLUSIONS: In CF patients diagnosed through neonatal screening, P aeruginosa pulmonary infections occurred 6 to 12 months before the organism was isolated from respiratory secretions. The longitudinal monitoring of P aeruginosa antibody titers, in concert with WCXR score, should facilitate diagnosis and treatment of P aeruginosa pulmonary infections in young children with CF.

ADP Ribose Transferases↗