Objective measurement of posture allocation and sedentary behaviours in the pre-school child: a validation study

Sedentary behaviours contribute to energy imbalance in young children. Time spent sitting may be an important component of sedentary behaviour but validated measures of posture and posture transitions in the pre-school child are lacking. Accelerometer based posture detection systems validated in the adult literature have often shown excellent agreement with the gold standard of direct observation in controlled environments, but their potential use for the young child is likely to be limited by weight and the need to use multiple sensor sites. Single unit sensors are a potentially more practical alternative that may be suitable for use in research involving young children. This thesis describes the validation of two single unit accelerometer based monitors for their ability to each measure posture and postural transition objectively: the activPAL (PAL Technologies, UK) and the DynaPort MicroMod MoveMonitor 1.2 (McRoberts, NL). It also compares sedentary behaviours as detected by the activPAL and DynaPort monitors with conventional accelerometry using the ActiGraph. The activPAL and DynaPort MoveMonitor algorithms for posture and activity identification in comparison to the gold standard of direct observation have been validated in adults. Neither has previously been validated in young children. A validation study of the activPAL and DynaPort MicroMod MoveMonitor involving 30 pre-school children is described. The study took place in each child’s usual nursery environment. Children were videoed for one hour undertaking usual activities in nursery while wearing an activPAL and DynaPort MicroMod. In addition, children also wore an ActiGraph accelerometer. The ActiGraph does not measure posture but is well established in physical activity research in childhood. It provided objective information about activity intensity (in particular sedentary behaviour) for each child during the observation period. Video (gold standard) was analyzed on a second-by-second basis and compared with monitor output. From direct video observation, the proportion of time spent during the one hour of video recording was sit/lie 46%; stand 35%; and walk 16%. The remaining 3% of time was spent in non-sit/lie/upright postures (e.g. crawl, crouch, kneel up) although transitions involving these contributed disproportionately to total posture transitions. The number of sit-stand posture transitions on direct observation was not associated with time spent sedentary. The overall proportion of time detected as ‘sit/lie’ was 42% and 32% as detected by activPAL and DynaPort respectively. Similarly, for activPAL and DynaPort detected ‘walk’, this was 16% and 15% respectively. Overall sensitivity for time detected as activPAL ‘sit/lie’ was 87%, specificity 97% and positive predictive value 96%. DynaPort MicroMod sensitivity for ‘sit’ was lower but specificity remained high (91%). There was poor correlation between activPAL ‘sit/lie’ and ActiGraph-defined sedentary behaviour (<1100 counts per minute), r = 0.16. However, there was good correlation (r=0.87) between activPAL [‘sit/lie’ + ‘stand’] and ActiGraph defined sedentary behaviour. The validation results for the activPAL were similar to those described in the adult literature and although those for the DynaPort monitor were less good, both show promise as measurement tools in this age group. Single unit accelerometers capable of detecting posture may have a role in the evaluation of sedentary behaviour in young children, beyond the capabilities of currently used objective monitors such as the ActiGraph. However the role of (and importance of objectively capturing) posture transitions, including non-sit/lie/upright postures requires further investigation. Ultimately, knowledge of posture and postural transitions may provide a better understanding of movement and activity in young children. This potential to help evaluate sedentary behaviours is of interest for childhood obesity research

The medical culture of the Ovambo of Southern Angola and Northern Namibia

This thesis focusses on the medical culture of the Ovambo peoples of southern Angola and northern Namibia, a group who have been little-researched anthropologically. Because health and affliction are such poignant human concerns, the study of a society's medical culture can tell us much about their social and cultural organisation in general. It is for this reason that Ovambo medical culture has been examined in relation to the wider socio-cultural background, rather than in isolation; especially since Ovambo evidence has shown that concern about health and affliction is not confined to the physical and spiritual wellbeing of individuals, but extends to include harmonious social relations, environmental and economic prosperity, and politicaly stability. A holistic analytical approach has been adopted, whereby all aspects of the medical culture are considered (insofar as the data allow), as opposed to only certain aspects. Ovambo beliefs and practises relating to healt hand health maintenance are therefore discussed, as well as external (i.e. European) medical influences. Particular attention has been paid to Ovambo use of plants as medicines, as well as to their prophylactic and propitiatory measures, since these are areas of athnomedical research that are identified as being under-researched. Focussing upon these areas has also highlighted the significance of material culture in the Ovambo medical domain, and the value of museum collections of ethnography in this regard

Inclusive or random? A study of verbal interaction between practitioners and children at pre-school settings.

This small scale study examined the function and frequency of verbal interaction between adults and children within pre-school settings. A range of data collection methods were utilised to ascertain whether practitioners listened to children’s views and encouraged dialogue and discourse inclusively. A mixed methodology design was chosen to enable effective data collection and analysis. Data collection methods were piloted before the main study to test for suitability and effectiveness. Provision in three sample settings was examined. Research literature relating to verbal interaction was reviewed. The study concluded that practitioners were well-qualified and versed in the philosophy of child-directed play, but were preoccupied with product-based activities to the detriment of effective verbal interactions with children. The study recommended methods for raising awareness among practitioners in order to improve the quality of interaction and dialogue within pre-school settings. These methods included a programme of self- and peer-evaluation, further training and visits to other early years settings

Emulated trial investigating effects of multiple treatments: estimating combined effects of mucoactive nebulisers in cystic fibrosis using registry data

Introduction: People with cystic fibrosis (CF) are often on multiple long-term treatments, including mucoactive nebulisers. In the UK, the most common mucoactive nebuliser is dornase alfa (DNase). A common therapeutic approach for people already on DNase is to add hypertonic saline (HS). The effects of DNase and HS used alone have been studied in randomised trials, but their effects in combination have not. This study investigates whether, for people already prescribed DNase, adding HS has additional benefit for lung function or use of intravenous antibiotics.// Methods: Using UK CF Registry data from 2007 to 2018, we emulated a target trial. We included people aged 6 years and over who were prescribed DNase without HS for 2 years. We investigated the effects of combinations of DNase and HS over 5 years of follow-up. Inverse-probability-of-treatment weighting was used to control confounding. The period predated triple combination CF transmembrane conductance regulator modulators in routine care.// Results: 4498 individuals were included. At baseline, average age and forced expiratory volume in 1 s (FEV1%) predicted were 21.1 years and 69.7 respectively. During first year of follow-up, 3799 individuals were prescribed DNase alone; 426 added HS; 57 switched to HS alone and 216 were prescribed neither. We found no evidence that adding HS improved FEV1% at 1–5 years, or use of intravenous antibiotics at 1–4 years, compared with DNase alone.// Conclusion: For individuals with CF prescribed DNase, we found no evidence that adding HS had an effect on FEV1% or prescription of intravenous antibiotics. Our study illustrates the emulated target trial approach using CF Registry data

Asthma and Th2 immunity: The impact of genetic factors and obesity.

Introduction: Th2 immune signalling is key to the pathological substrate of asthma. The primary objective of this thesis was to identify the predictive effects of genetic variants of Th2 signalling at the population level, and to examine interactions between different loci, with relation to asthma and associated phenotypes. This genetic epidemiological study provided an opportunity to explore also the predictive effects of different measures of obesity on these phenotypes. Methods: An unselected population of 1614 young adults was recruited. Responses to validated questionnaires and spirometry provided clinical and physiological asthma phenotypes. Anthropometry provided the measures of obesity. Assays on venous blood provided immune phenotypes (IgE, eosinophils, eotaxin). Genotyping encompassed 22 polymorphisms in the 1L13, IL4RA and STAT6 genes, representing the Th2 immune signalling pathway. Data analysis used linear and logistic regression models, and a modified regression to address haplotypes. Results: Single polymorphisms and hapiotypes of IL13, IL4RA and STAT6 loci significantly predicted asthma, eczema and hayfever at the population level. Several novel associations were shown for serum IgE levels and airflow obstruction. Significant interaction (epistasis) was identified between variants of IL13 and STAT6 for total IgE levels. Adiposity indices (BMI, waist circumference, body fat) showed consistent associations with asthma and airflow obstruction, but also with Th2 inflammatory markers (IgE, eotaxin and eosinophils) with modulation by sex/smoking status. Conclusions: Genetic variants of Th2 immune signalling are one important source of risk for asthma and allergy in the general population, with variants operating both singly and in combination. Obesity and its causes are also likely to be significant contributors to the occurrence of asthma in the population, and may operate through pro- inflammatory mechanisms. These findings exemplify the polygenic and multifactorial determination of asthma and allergy, through genetic and environmental effects

Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and covid-19: phase 3 randomised controlled trial (CORONAVIT)

Objective To determine the effect of population level implementation of a test-and-treat approach to correction of suboptimal vitamin D status (25-hydroxyvitamin D (25(OH)D) <75 nmol/L) on risk of all cause acute respiratory tract infection and covid 19.Design Phase 3 open label randomised controlled trial.Setting United Kingdom.Participants 6200 people aged ≥16 years who were not taking vitamin D supplements at baseline.Interventions Offer of a postal finger prick test of blood 25(OH)D concentration with provision of a six month supply of lower dose vitamin D (800 IU/day, n=1550) or higher dose vitamin D (3200 IU/day, n=1550) to those with blood 25(OH)D concentration <75 nmol/L, compared with no offer of testing or supplementation (n=3100). Follow-up was for six months.Main outcome measures The primary outcome was the proportion of participants with at least one swab test or doctor confirmed acute respiratory tract infection of any cause. A secondary outcome was the proportion of participants with swab test confirmed covid-19. Logistic regression was used to calculate odds ratios and associated 95% confidence intervals. The primary analysis was conducted by intention to treat.Results Of 3100 participants offered a vitamin D test, 2958 (95.4%) accepted and 2674 (86.3%) had 25(OH)D concentrations <75 nmol/L and received vitamin D supplements (n=1328 lower dose, n=1346 higher dose). Compared with 136/2949 (4.6%) participants in the no offer group, at least one acute respiratory tract infection of any cause occurred in 87/1515 (5.7%) in the lower dose group (odds ratio 1.26, 95% confidence interval 0.96 to 1.66) and 76/1515 (5.0%) in the higher dose group (1.09, 0.82 to 1.46). Compared with 78/2949 (2.6%) participants in the no offer group, 55/1515 (3.6%) developed covid-19 in the lower dose group (1.39, 0.98 to 1.97) and 45/1515 (3.0%) in the higher dose group (1.13, 0.78 to 1.63).Conclusions Among people aged 16 years and older with a high baseline prevalence of suboptimal vitamin D status, implementation of a population level test-and-treat approach to vitamin D supplementation was not associated with a reduction in risk of all cause acute respiratory tract infection or covid-19

Effect of High-Intensity Training and Asthma on the VO2 Kinetics of Adolescents

Purpose High-intensity interval training (HIIT) represents a potent stimulus to the dynamic oxygen uptake (V[Combining Dot Above]O2) response in adults but whether the same is evident in youth is unknown. HIIT has also been suggested to place a lower demand on the respiratory system, decreasing the likelihood of exacerbation in those with respiratory conditions, such as asthma.Methods Sixty-nine adolescents (13.6±0.9 years; 36 asthma) took part, 35 of which (17 asthma) participated in a 30-minute HIIT intervention three-times/week for six months. Each participant completed an incremental ramp test to volitional exhaustion and three heavy-intensity constant work-rate tests to determine the dynamic oxygen uptake (V[Combining Dot Above]O2), heart rate (HR) and deoxyhaemoglobin ([HHb]) response at baseline, mid-intervention, post-intervention and at a three-month follow-up.Results There was no influence of asthma at baseline or in response to the intervention. Participants in the intervention group demonstrated a faster V[Combining Dot Above]O2 time constant (τp) post-intervention (intervention: 29.2±5.7 vs. control: 34.2±6.5 s; P=0.003), with these differences maintained at follow-up (intervention: 32.5±5.5 vs. control: 37.3±8.7 s; P=0.008). The intervention was associated with a speeding of the [HHb] τ (Pre: 20.1±4.7 vs. Post: 18.2±4.1 s; P=0.05), compared to a slowing over the same time period in the control participants (Pre: 17.9±4.9 vs. Post: 20.1±4.6 s; P=0.012). HR kinetics were not altered (Pre: 46.5±12.2 vs. Post: 47.7±11.1 s; P=0.98).Conclusion These findings highlight the potential utility of school-based HIIT as a strategy to enhance the V[Combining Dot Above]O2 kinetics of youth, regardless of the presence of asthma

Inspiratory Muscle Training Enhances Recovery Post COVID-19: A Randomised Controlled Trial

Background: Many people recovering from COVID-19 experience prolonged symptoms, particularly breathlessness. We urgently need to identify safe and effective COVID-19 rehabilitative strategies. The aim of the current study was to investigate the potential rehabilitative role of inspiratory muscle training (IMT).Methods: 281 adults (46.6±12.2 years; 88% female) recovering from self-reported COVID-19 (9.0±4.2 months post-acute infection) were randomized 4:1 to an eight-week IMT or a “usual care” wait list control arm. Health-related quality of life and breathlessness questionnaires (King’s Brief Interstitial Lung Disease (KBILD) and Transition Dyspnoea Index (TDI)), respiratory muscle strength and fitness (Chester Step Test) were assessed pre- and post-intervention. The primary endpoint was KBILD total score, with the KBILD subdomains and TDI being key secondary outcomes. Results: According to intention to treat (ITT), there was no difference between groups in KBILD total score post-intervention (Control: 59.5±12.4; IMT: 58.2±12.3; P<0.05) but IMT elicited clinically meaningful improvements in the KBILD subdomains of breathlessness (Control: 59.8±12.6; IMT: 62.2±16.2; P<0.05) and chest symptoms (Control: 59.2±18.7; IMT: 64.5±18.2; P<0.05), along with clinically meaningful improvements in breathlessness according to TDI (Control: 0.9 ± 1.7 vs. 2.0 ± 2.0; P<0.05). IMT also improved respiratory muscle strength and estimated aerobic fitness. Conclusions: IMT may represent an important home-based rehabilitation strategy for wider implementation as part of COVID-19 rehabilitative strategies. Given the diverse nature of long-COVID, further research is warranted on the individual responses to rehabilitation - the withdrawal rate herein highlights that no one strategy is likely to be appropriate for all