Relation of changes in peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) during bronchoconstriction.

Diagnosis of asthma can be confirmed based on variability in peak expiratory flow (PEF) or changes in forced expiratory volume in 1 s (FEV1) measured with spirometry. Our aim was to use methacholine challenge as a model of induced airway obstruction to assess how well relative changes in PEF reflect airway obstruction in comparison to relative changes in FEV1. We retrospectively studied 878 patients who completed a methacholine challenge test. To assess congruency along with differences between relative changes in FEV1 and PEF during airway obstruction, a regression analysis was performed, and a Bland & Altman plot was constructed. ROC analysis, sensitivity, specificity, positive and negative predictive values and κ-coefficient were used to analyze how decrease in PEF predicts decrease of 10% or 15% in FEV1. The relative change in PEF was on average less than the relative change in FEV1. In the ROC analysis areas under the curve were 0.844 and 0.893 for PEF decrease to predict a 10% and 15% decrease in FEV1, respectively. The agreement between changes in PEF and FEV1 varied from fair to moderate. Airway obstruction detected by change in PEF was false in about 40% of cases when compared to change in FEV1. Change in PEF is not a very accurate measure of airway obstruction when compared to change in FEV1. Replacing peak flow metre with a handheld spirometer might improve diagnostic accuracy of home monitoring in asthma.

Relation of changes in PEF and FEV1 in exercise challenge in children.

Decrease in forced expiratory volume in one second (FEV1 ) of 10% or 15% in exercise challenge test is considered diagnostic for asthma, but a decrease of 15% in peak expiratory flow (PEF) is recommended as an alternative. Our aim was to assess the accuracy of different PEF cut-off points in comparison to FEV1 . We retrospectively studied 326 free running exercise challenge tests with spirometry in children 6-16 years old. FEV1 and PEF were measured before and 2, 5, 10 and 15 min after exercise. Receiver operating characteristics (ROC) analysis, sensitivity, specificity, positive and negative predictive values (PPV and NPV) and Ï°-coefficient were used to analyse how decrease in PEF predicts decrease of 10% or 15% in FEV1 . In the ROC analysis, areas under the curve were 0.851 (p < 0.001) and 0.921 (p < 0.001) for PEF decrease to predict a 10% and 15% decrease in FEV1 , respectively. The agreement between changes in PEF and FEV1 varied from slight to substantial (Ï° values of 0.199-0.680) depending on the cut-points. Lower cut-off for decrease in PEF had higher sensitivity and NPV, while higher cut-off values had better specificity and PPV. Decrease of 20% and 25% in PEF seemed to be the best cut-offs for detecting 10% and 15% decrease in FEV1 , respectively. Still, a fifth of the positive findings based on PEF were false. Change in PEF is not a precise predictor of change in FEV1 in exercise test. The currently recommended cut-point of 15% decrease in PEF seems to be too low and leads to high false positive rate.

Antenatal interventions to address harmful behaviors and psychosocial risk factors in the prevention of low birth weight.

BACKGROUND: Risk factors related to the harmful behaviors, psychosocial wellbeing, and socio-economic circumstances in the lives of pregnant women can lead to adverse birth outcomes, including low birth weight (LBW). OBJECTIVE: This systematic search and review aims to provide a comparative evidence synthesis on the effect of eleven antenatal interventions targeted to address psychosocial risk factors on adverse birth outcomes. METHODS: We searched MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials and CINAHL Complete between March 2020 and May 2020. We included randomized controlled trials (RCTs) and reviews of RCTs of eleven antenatal interventions for pregnant females reporting LBW, preterm birth (PTB), small-for-gestational-age or stillbirth as outcomes. For interventions where randomization was either not feasible or unethical, we accepted non-randomized controlled studies. RESULTS: Seven records contributed data to the quantitative estimates of the effect sizes and 23 contributed to narrative analysis. Psychosocial interventions for reducing smoking in pregnancy likely reduced the risk of LBW, and professionally provided psychosocial support for at-risk women possibly reduced the risk of PTB. Financial incentives or nicotine replacement therapy as smoking cessation aids, or virtually delivered psychosocial support did not appear to reduce the risk of adverse birth outcomes. The available evidence on these interventions was primarily from high-income countries. For other reviewed interventions (psychosocial interventions to reduce alcohol use, group based psychosocial support programs, intimate partner violence prevention interventions, antidepressant medication, and cash transfers) there was little evidence in any direction regarding the efficacy or the data was conflicting. CONCLUSIONS: Professionally provided psychosocial support during pregnancy in general and specifically as a means to reduce smoking can potentially contribute to improved newborn health. The gaps in the investments for research and implementation of psychosocial interventions should be addressed to better meet the global targets in LBW reduction.