Screening for Pulmonary disease

Background
Respiratory conditions are found in children with SCD at a prevalence of 20 percent to 48 percent and are associated with an increased risk of mortality. In a prospective study of 1,963 individuals with SCA followed from birth through adulthood, individuals with SCA and asthma had a more than twofold higher risk of mortality after adjusting for established risk factors. In assessing asthma characteristics in an observational study of 79 adults with SCD who completed respiratory symptom questionnaires, those who reported recurrent, severe episodes of wheezing (n=34), regardless of asthma, had twice the rates of pain, ACS, decreased lung function, and increased risk of death compared with adults without recurrent, severe wheezing.
Pulmonary function tests (PFTs) provide a method for objectively assessing the function of the respiratory system. Although multiple studies have demonstrated abnormal pulmonary function in children and adults with SCD, little has been reported regarding the meaning of these changes for the functional status or quality of life in people with SCD. No therapies have been suggested to address these changes unless the person is also shown to have another lung disease, such as asthma, chronic obstructive pulmonary disease (COPD), or pulmonary fibrosis. The utility of screening for respiratory disorders in children and adults using PFTs has not been established. A study to characterize the polysomnographic (PSG) findings of children with SCD who displayed behaviors suspicious of sleep disorder (ri=100) identified using the Children’s Sleep Habit Questionnaire found sleep-disordered breathing (SDB) in 79 percent of the SCD group. Compared to children with obstructive sleep apnea syndrome (OSAS) without medical comorbidities, children with SCD and OSAS experienced nocturnal desaturation with a fourfold increased risk for oxygen desaturation below 85 percent and hypercapnia. Therefore, routinely taking a thorough respiratory history is valuable to evaluate symptoms that may require further assessment.

Summary of the Evidence
Thirty-four studies (11 longitudinal and 23 cross-sectional) described the results of screening using PFTs in people with SCD who had no recognized respiratory symptoms. No study evaluated the utility of screening or compared an approach of screening versus no screening, and there were no data on diagnostic accuracy.
Overall, it was unclear whether early intervention was beneficial or whether screening was cost-effective. Screening intervals were not assessed. The supporting quality of evidence was considered low.
The longitudinal and cross-sectional studies enrolled more than 1,500 and 1,700 subjects, respectively. Children with SCA had lower forced expiratory volume at 1 minute (FEV,), forced vital capacity (FVC), and forced expiratory flow (FEF) 25-75 and slower lung growth curves (FEV t and FEV t/FVC) compared to controls.Lung volume, as a percentage of that predicted, was demonstrated to decline with age in children with SCD, similar to the decline noted in children with cystic fibrosis. A cross-sectional study of African American adults with SLA enrolled in the Cooperative Study of Sickle Cell Disease revealed abnormalities in 90 percent of the subjects (279 of 310). The most common abnormality was a restrictive pattern (74 percent) with isolated decreased diffusing capacity observed in 13 percent of the patients. Other studies demonstrated obstructive changes in 15-21 percent of children and adults with SCD, restrictive changes in 22-27 percent of adults with

SCD, and mixed restrictive/obstructive changes in 6-12 percent of adults with SCD. Compared with controls, people with SCD had lower FVC, FEV t, and peak expiratory flow rate (PEFR). When corrected for hemoglobin levels, children with SCA compared to controls of similar age had elevated gas transfer per unit lung volume. People with HbSC also appear to have lung function abnormalities, which are milder than those seen in people with HbSS. No studies discussed any type of intervention for children or adults with SCD and abnormal lung function.

Recommendations
1. In children and adults with SCD, assess for signs and symptoms of respiratory problems (such as asthma, COPD, restrictive lung disease, or obstructive sleep apnea) by history and physical examination. (Consensus—Pane/Expertise)
2. In children and adults with SCD found to have signs or symptoms of respiratory problems by history and/or physical examination, further assessment, which includes pulmonary function tests, is recommended to determine the cause and develop a plan to address the problem.
(Consensus—Pane/Expertise)
3. Do not screen asymptomatic children and adults with pulmonary function tests.
(Moderate Recommendation, Low quality Evidence)