Low birth weight and respiratory hospitalizations in adolescence.

OBJECTIVE: Some low birth weight survivors are at increased risk of respiratory disease. We studied whether low birth weight was associated with hospitalization for respiratory illness in adolescence and to what degree bronchopulmonary dysplasia, cerebral palsy, and other comorbidities accounted for this association. METHODS: We performed a population-based retrospective cohort study using Washington State birth certificates from 1987 to 1994 to identify exposed (low birth weight) and unexposed (normal birth weight) subjects. Normal birth weight subjects were randomly selected from birth certificates, frequency matched to low birth weight subjects by birth year. Deaths prior to age 12 were excluded. The primary exposure was low birth weight: subcategorized as moderately-low-birth weight (1,500-2,499 g) and very-low-birth weight (<1,500 g). The primary outcome was the first respiratory related hospitalization between the ages of 12-20. Respiratory hospitalizations were defined by ICD-9 discharge diagnosis codes. RESULTS: After adjustment, the hazard ratio for hospitalization was 1.39 for moderately-low-birth weight (95% CI 1.17-1.65, P < 0.001) and 2.52 for very-low-birth weight (1.80-3.53, P < 0.001). Controlling for bronchopulmonary dysplasia attenuated the risk for very-low-birth weight to 1.76 (1.17-2.64; P = 0.006). A similar attenuation was seen after controlling for cerebral palsy [HR 1.49 (1.02-2.18), P = 0.04], suggesting that some of the risk is mediated through these diagnoses. Among moderately-low-birth weight survivors, controlling for these diagnoses had less of an effect. CONCLUSIONS: Low birth weight was associated with an increased risk of respiratory hospitalizations in adolescence. Comorbidities explained some of this risk. However, low birth weight remained independently associated with an increased risk of hospitalization.

Lung function and long-term complications after allogeneic hematopoietic cell transplant.

It is unknown if diminished pulmonary function early after allogeneic hematopoietic transplant is associated with poor long-term outcomes. The objective of this study was to determine if posttransplant lung function is associated with 5-year nonrelapse mortality (NRM) and the development of chronic graft-versus-host disease (cGVHD). Retrospective analysis was done for 2158 patients who had routine pulmonary function testing 60-120 days after transplant between 1992 and 2004. Cox regression was used to assess the hazard ratio for 5-year NRM. A second analysis assessed the hazard ratio for the development of cGVHD. Lung function score was the primary exposure, and was calculated according to forced expiratory volume in 1 second (FEV(1)) and carbon monoxide diffusion capapcity (DLCO). Individual pulmonary function parameters were secondary exposures. The primary outcomes were 5-year NRM and the development of cGVHD. Most patients had normal lung function following transplant. A higher lung function score, signifying greater impairment, was associated with an increased risk of mortality (category 1 hazard ratio [HR] 1.47 [1.17-1.85]; category 2 HR 3.38 [2.53-4.53]; category 3 HR 7.80 [4.15-14.68]). A similar association was observed for all individual pulmonary function parameters. Low FEV(1) was associated with the subsequent development of cGVHD (FEV(1) 70%-79% HR 1.26 [1.01-1.57]; 60%-69% HR 1.48 [1.10-2.01]; <60% HR 2.02 [1.34-3.05]). Models using either lung function score or individual pulmonary function parameters performed about equally well as judged by the C-statistic. Impaired lung function at day 80 posttransplant was associated with a higher risk of NRM. A low FEV(1) following transplant was associated with developing cGVHD within 1 year.

Influence of pretransplantation restrictive lung disease on allogeneic hematopoietic cell transplantation outcomes.

We conducted a 15-year retrospective cohort study to determine the prevalence of restrictive lung disease before allogeneic hematopoietic cell transplantation (HCT), and to assess whether this was a risk factor for poor outcomes. A total of 2545 patients were eligible for the analysis. Restrictive lung disease was defined as a total lung capacity (TLC) < 80% of predicted normal. Chest x-rays and /or computed tomography (CT) scans were reviewed for all restricted patients to determine whether lung parenchymal abnormalities were unlikely or highly likely to cause restriction. Multivariate Cox proportional hazard and sensitivity analyses were performed to assess the relationship between restriction and early respiratory failure and nonrelapse mortality. Restrictive lung disease was present in 194 subjects (7.6%) before HCT. Among these cases, radiographically apparent abnormalities were unlikely to be the cause of the restriction in 149 subjects (77%). In unadjusted and adjusted analyses, the presence of pulmonary restriction was significantly associated with a 2-fold increase in risk for early respiratory failure and nonrelapse mortality, suggesting that these outcomes occurring in the absence of radiographically apparent abnormalities may be related to respiratory muscle weakness. These findings suggest that pulmonary restriction should be considered a risk factor for poor outcomes after transplantation.

Low birth weight and respiratory disease in adulthood: a population-based case-control study.

RATIONALE: The proportion of low and very low birth weight births is increasing. Infants and children with a history of low and very low birth weight have an increased risk of respiratory illnesses, but it is unknown if clinically significant disease persists into adulthood. OBJECTIVES: To determine if a history of low birth weight is associated with hospitalization for respiratory illness in adulthood. METHODS: This study was a population-based, case-control study. Cases were adults 18 to 27 years of age who were hospitalized for a respiratory illness from 1998 to 2007 within Washington State who could be linked to a Washington State birth certificate for the years 1980 to 1988. Four control subjects, frequency matched by birth year, were randomly selected from Washington State birth certificates for each case patient. Control subjects who died before age 18 were excluded. MEASUREMENTS AND MAIN RESULTS: Two levels of exposure were identified: (1) very low birth weight (birth weight <1,500 g) and (2) moderately low birth weight (birth weight, 1,500-2,499 g). Normal birth weight individuals (2,500-4,000 g) were considered unexposed. Respiratory hospitalizations were defined using discharge diagnosis codes. Logistic regression was used to calculate the odds ratio for hospitalization comparing exposed and unexposed individuals. A total of 4,674 case patients and 18,445 control subjects were identified. The odds ratio for hospitalization for respiratory illness was 1.83 for very low birth weight (95% confidence interval, 1.28-2.62; P = 0.001) and 1.34 for moderately low birth weight (95% confidence interval, 1.17-1.53; P < 0.0005). This association remained after adjustment for birth year, sex, maternal age, race, residence, and marital status. CONCLUSIONS: Adults with a history of very low birth weight or moderately low birth weight were at increased risk of hospitalization for respiratory illness.