Participant retention in follow-up studies of prematurely born children.

BACKGROUND: Follow-up studies of infants born prematurely are essential to understand the long-term consequences of preterm birth and the efficacy of interventions delivered in the neonatal period. Retention of participants for follow-up studies, however, is challenging, with attrition rates of up to 70%. Our aim was to examine retention rates in two follow-up studies of prematurely born children and identify participant or study characteristics that were associated with higher attrition, and to discuss retention strategies with regard to the literature. METHODS: Data from children recruited at birth to one of two studies of prematurely born infants were assessed. The two studies were the United Kingdom Oscillation Study (UKOS, a randomised study comparing two modes of neonatal ventilation in infants born less than 29 weeks of gestational age (GA)), and an observational study examining the impact of viral lower respiratory tract infections in infancy in those born less than 36 weeks of GA (virus study). The UKOS participants, but not those in the virus study, had regularly been contacted throughout the follow-up period. UKOS subjects were followed up at 11 to 14 years of age and subjects in the virus study at 5-7 years of age. At follow up in both studies, pulmonary function and respiratory morbidity were assessed. Retention rates to follow-up in the two studies and baseline characteristics of those who were and were not retained were assessed. RESULTS: Retention was significantly higher in UKOS than the virus study (61% versus 35%, p < 0.0001). Subjects lost to UKOS follow up had greater deprivation scores (p < 0.001), a greater likelihood of intrauterine tobacco exposure (p = 0.001) and were more likely to be of non-white ethnicity (p < 0.001). In the virus study, those lost to follow-up had higher birth weights (p = 0.036) and were less likely to be oxygen dependent at hospital discharge (p = 0.003) or be part of a multiple birth (p = 0.048). CONCLUSIONS: Higher retention was demonstrated when there was regular contact in the follow-up period. Both social factors and initial illness severity affected the retention into follow-up studies of prematurely born infants, though these factors were not consistent across the two studies.

Respiratory viral infections in infancy and school age respiratory outcomes and healthcare costs.

OBJECTIVES: To determine the impact of viral lower respiratory tract infections (LRTIs) in infancy including rhinovirus (RV) and infancy respiratory syncytial virus (RSV), on school age pulmonary function and healthcare utilization in prematurely born children. WORKING HYPOTHESIS: School age respiratory outcomes would be worse and healthcare utilization greater in children who had viral LRTIs in infancy. STUDY DESIGN: Prospective study. SUBJECT SELECTION: A cohort of prematurely born children who had symptomatic LRTIs during infancy documented, was recalled. METHODS: Pulmonary function was assessed at 5 to 7 years of age and health related costs of care from aged one to follow-up determined. RESULTS: Fifty-one children, median gestational age 33+6 weeks, were assessed at a median (IQR) age 7.03 (6.37-7.26) years. Twenty-one children had no LRTI, 14 RV LRTI, 10 RSV LRTI, and 6 another viral LRTI (other LRTI). Compared to the no LRTI group, the RV group had a lower FEV1 (P = 0.033) and the other LRTI group a lower FVC (P = 0.006). Non-respiratory medication costs were higher in the RV (P = 0.018) and RSV (P = 0.013) groups. Overall respiratory healthcare costs in the RV (£153/year) and RSV (£27/year) groups did not differ significantly from the no LRTI group (£56/year); the other LRTI group (£431/year) had higher respiratory healthcare costs (P = 0.042). CONCLUSIONS: In moderately prematurely born children, RV and RSV LRTIs in infancy were not associated with higher respiratory healthcare costs after infancy. Children who experienced LRTIs caused by other respiratory viruses (including RV) had higher respiratory healthcare costs and greater pulmonary function impairment.

Nonvolitional assessment of tibialis anterior force and architecture during critical illness.

INTRODUCTION: Contemporaneous measures of muscle architecture and force have not previously been conducted during critical illness to examine their relationship with intensive care unit (ICU)-acquired weakness. METHODS: Ankle dorsiflexor muscle force (ADMF) with high-frequency electrical peroneal nerve stimulation and skeletal muscle architecture via ultrasound were measured in 21 adult, critically ill patients, 16 at ICU admission. RESULTS: Thirteen patients were measured on 2 occasions. Among these, 10 who were measured at ICU admission demonstrated muscle weakness. Despite significant reductions in tibialis anterior (Δ = -88.5 ± 78.8 mm2 , P = 0.002) and rectus femoris (Δ = -126.1 ± 129.1 mm2 , P = 0.006) cross-sectional areas between occasions, ADMF did not change (100-HZ ankle dorsiflexor force 9.8 [IQR, 8.0-14.4] kg vs. 8.6 (IQR, 6.7-19.2) kg, P = 0.9). DISCUSSION: Muscle weakness was evident at ICU admission. No additional decrements were observed 7 days later despite significant reductions in muscle size. These data suggest that not all ICU weakness is truly "acquired" and questions our understanding of muscle function during critical illness. Muscle Nerve 57: 964-972, 2018.

Ultrasound for the assessment of peripheral skeletal muscle architecture in critical illness: a systematic review.

OBJECTIVES: To critically evaluate and summarize identified evidence for the use of ultrasound to measure peripheral skeletal muscle architecture during critical illness. DATA SOURCES: Seven electronic databases (Medline, Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, Physiotherapy Evidence Database, Scopus, Excerpta Medica Database, and Web of Science [including Science Citations and Conference Proceedings]) and personal libraries were searched for relevant articles. Cross-referencing further identified references. STUDY SELECTION: Quantitative study designs excluding abstracts, published in English, including adult critically ill patients in the ICU, evaluating peripheral skeletal muscle architecture during critical illness with ultrasound were included. Studies using ultrasonographic muscle data as outcome measures in interventional trials were excluded. DATA EXTRACTION: Performed by one reviewer using a standardized data extraction form and cross-checked by a second reviewer. Quality appraisal was undertaken by two independent reviewers-studies were classified, graded, and appraised according to standardized algorithms and checklists. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were adhered to. DATA SYNTHESIS: Seven studies with independent patient cohorts totaling 300 participants were included. One study adopted a case-control design, and the remainder were case series. Ultrasound data demonstrated deficits in a variety of peripheral skeletal muscle architecture variables across a range of muscle groups associated with critical illness. Ultrasound offered more accurate data compared to limb circumference measurement and has excellent reported reliability, but underestimated data acquired via more invasive muscle biopsy. CONCLUSION: Ultrasound provides clinical utility for assessing the trajectory of change in peripheral skeletal muscle architecture during critical illness, supplementing more detailed characterization, albeit rarely used, from muscle biopsy analysis. Adoption of standardized operating protocols for measurement will facilitate future meta-analysis of data.