Inert tracer gas washout (IGW) measurements detect increased ventilation inhomogeneity (VI) in chronic lung diseases. Their suitability for different diseases, such as cystic fibrosis (CF) and primary ciliary dyskinesia (PCD), has already been shown. However, it is still unclear if physiological phenotypes based on different IGW variables can be defined independently of underlying disease. Eighty school-age children, 20 with CF, 20 with PCD, 20 former preterm children, and 20 healthy children, performed nitrogen multiple-breath washout, double-tracer gas (DTG) single-breath washout, and spirometry. Our primary outcome was the definition of physiological phenotypes based on IGW variables. We applied principal component analysis, hierarchical Ward's clustering, and enrichment analysis to compare clinical characteristics between the clusters. IGW variables used for clustering were lung clearance index (LCI) and convection-dependent [conductive ventilation heterogeneity index (Scond)] and diffusion-convection-dependent variables [acinar ventilation heterogeneity index (Sacin) and carbon dioxide and DTG phase III slopes]. Three main phenotypes were identified. Phenotype I (n = 38) showed normal values in all IGW outcome variables. Phenotype II (n = 21) was characterized by pronounced global and convection-dependent VI while diffusion-dependent VI was normal. Phenotype III (n = 21) was characterized by increased global and diffusion- and convection-dependent VI. Enrichment analysis revealed an overrepresentation of healthy children and former preterm children in phenotype I and of CF and PCD in phenotypes II and III. Patients in phenotype III showed the highest proportion and frequency of exacerbations and hospitalization in the year prior to the measurement. IGW techniques allow identification of clinically meaningful, disease-independent physiological clusters. Their predictive value of future disease outcomes remains to be determined.

Objectives To determine the prevalence of use of complementary medicine (CM) in Switzerland in 2017, its development since the 2012 Swiss Health Survey, and to examine specific and non-specific sociodemographic, lifestyle and health-related determinants of CM use as compared to determinants of conventional health care use. Materials and methods We used data of 18,832 participants from the cross-sectional Swiss Health Survey conducted by the Swiss Federal Statistical Office in 2017 and compared these data with those from 2012. We defined four CM categories: (1) traditional Chinese medicine, including acupuncture; (2) homeopathy; (3) herbal medicine; (4) other CM therapies (shiatsu, reflexology, osteopathy, Ayurveda, naturopathy, kinesiology, Feldenkrais, autogenic training, neural therapy, bioresonance therapy, anthroposophic medicine). Independent determinants of CM use and of conventional health care use were assessed using multivariate weighted logistic regression models. Results Prevalence of CM use significantly increased between 2012 and 2017 from 24.7% (95% CI: 23.9–25.4%) to 28.9% (95% CI: 28.1–29.7%), respectively, p<0.001). We identified the following independent specific determinants of CM use: gender, nationality, age, lifestyle and BMI. Female gender and nationality were the most specific determinants of CM use. Current smoking, being overweight and obesity were determinants of non-use of CM, while regular consumption of fruits and/or vegetables and regular physical activity were determinants of CM use. Conclusion Prevalence of CM use significantly increased in Switzerland from 2012 to 2017. Gender, nationality, age, lifestyle and BMI were independent specific determinants of CM use as compared to conventional health care use. Healthier lifestyle was associated with CM use, which may have potentially significant implications for public health and preventive medicine initiatives. The nationality of CM users underlines the role of culture in driving the choice to use CM but also raises the question of whether all populations have equal access to CM within a same country.

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