A Systematic Literature Review on Machine and Deep Learning Approaches for Detecting Attacks in RPL-Based 6LoWPAN of Internet of Things.

The IETF Routing Over Low power and Lossy network (ROLL) working group defined IPv6 Routing Protocol for Low Power and Lossy Network (RPL) to facilitate efficient routing in IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN). Limited resources of 6LoWPAN nodes make it challenging to secure the environment, leaving it vulnerable to threats and security attacks. Machine Learning (ML) and Deep Learning (DL) approaches have shown promise as effective and efficient mechanisms for detecting anomalous behaviors in RPL-based 6LoWPAN. Therefore, this paper systematically reviews and critically analyzes the research landscape on ML, DL, and combined ML-DL approaches applied to detect attacks in RPL networks. In addition, this study examined existing datasets designed explicitly for the RPL network. This work collects relevant studies from five major databases: Google Scholar, Springer Link, Scopus, Science Direct, and IEEE Xplore® digital library. Furthermore, 15,543 studies, retrieved from January 2016 to mid-2021, were refined according to the assigned inclusion criteria and designed research questions resulting in 49 studies. Finally, a conclusive discussion highlights the issues and challenges in the existing studies and proposes several future research directions.

Compression-Aware Aggregation and Energy-Aware Routing in IoT-Fog-Enabled Forest Environment.

Forest fire monitoring is very much needed for protecting the forest from any kind of disaster or anomaly leading to the destruction of the forest. Now, with the advent of Internet of Things (IoT), a good amount of research has been done on energy consumption, coverage, and other issues. These works did not focus on forest fire management. The IoT-enabled environment is made up of low power lossy networks (LLNs). For improving the performance of routing protocol in forest fire management, energy-efficient routing protocol for low power lossy networks (E-RPL) was developed where residual power was used as an objective function towards calculating the rank of the parent node to form the destination-oriented directed acyclic graph (DODAG). The challenge in E-RPL is the scalability of the network resulting in a long end-to-end delay and less packet delivery. Additionally, the energy of sensor nodes increased with different transmission range. So, for obviating the above-mentioned drawbacks in E-RPL, compressed data aggregation and energy-based RPL routing (CAA-ERPL) is proposed. The CAA-ERPL is compared with E-RPL, and the performance is analyzed resulting in reduced packet transfer delay, less energy consumption, and increased packet delivery ratio for 10, 20, 30, 40, and 50 nodes. This has been evaluated using a Contiki Cooja simulator.

On-Demand Scheduling of Command and Responses for Low-Power Multihop Wireless Networks.

Many IoT applications require a mechanism to disseminate commands and collect responses over a wireless network in order to control and collect data from multiple embedded devices. However, severe collisions may occur if a large number of nodes attempt to respond simultaneously and promptly, not only among the responses, but also with the dissemination of commands. This is because low-power wireless network protocols for dissemination and collection have been designed separately. Tuning the parameters of one side of the protocol has clear trade-off between reliability and latency. To address this challenge, we propose SCoRe, an on-demand scheme for joint scheduling of command and responses on multihop low-power wireless networks to improve both reliability and latency simultaneously at runtime. SCoRe gathers the amount of time required by network nodes for dissemination and collection, and allocates relative timeslots to each node recursively over multihop on-demand when (and only when) disseminating a command. While doing so, information exchange occurs only between local neighbor nodes without a need for global routing table nor time synchronization. We implement SCoRe on a low-power embedded platform, and compare with well-known dissemination and collection schemes through both simulations and testbed experiments on 30 devices. Our evaluation results show that SCoRe can improve both latency and reliability without tuning the parameters for one metric, while the legacy schemes require careful parameter selection to match only one side of SCoRe, never both.

DYNASTI-Dynamic Multiple RPL Instances for Multiple IoT Applications in Smart City.

Internet of Things (IoT) is evolving to multi-application scenarios in smart cities, which demand specific traffic patterns and requirements. Multi-applications share resources from a single multi-hop wireless networks, where smart devices collaborate to send collected data over a Low-Power and Lossy Networks (LLNs). Routing Protocol for LLNs (RPL) emerged as a routing protocol to be used in IoT scenarios where the devices have limited resources. Instances are RPL mechanisms that play a key role in order to support the IoT scenarios with multiple applications, but it is not standardized yet. Although there are related works proposing multiple instances in RPL on the same IoT network, those works still have limitations to support multiple applications. For instance, there is a lack of flexibility and dynamism in management of multiple instances and service differentiation for applications. In this context, the goal of this work is to develop a solution called DYNAmic multiple RPL instanceS for multiple ioT applicatIons (DYNASTI), which provides more dynamism and flexibility by managing multiple instances of RPL. As a result of this, the traffic performance of multiple applications is enhanced through the routing, taking into consideration the distinct requirements of the applications. In addition, DYNASTI enables the support of sporadic applications as well as the coexistence between regular and sporadic applications. DYNASTI achieved results that demonstrate a significant improvement in reducing the number of control messages, which resulted in increased packet received, decreased end-to-end delay, reduced energy consumption, and an improvement in service differentiation to multiple applications.

Global lung function initiative 2012 reference values for spirometry in Asian Americans.

BACKGROUND: Spirometry reference values specifically designed for Asian Americans are currently unavailable. The performance of Global Lung Function Initiative 2012 (GLI-2012) equations on assessing spirometry in Asian Americans has not been evaluated. This study aimed to assess the fitness of relevant GLI-2012 equations for spirometry in Asian Americans. METHODS: Asian subjects who never smoked and had qualified spirometry data were extracted from the National Health and Nutrition Examination Survey (NHANES) 2011-2012. Z-scores of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC were separately constructed with GLI-2012 equations for North East (NE) Asians, South East (SE) Asians, and individuals of mixed ethnic origin (Mixed). In addition, Proportions of subjects with observed spirometry data below the lower limit of normal (LLN) were also evaluated on each GLI-2012 equation of interest. RESULTS: This study included 567 subjects (250 men and 317 women) aged 6-79 years. Spirometry z-scores (z-FEV1, z-FVC, and z-FEV1/FVC) based on GLI-2012 Mixed equations had mean values close to zero (- 0.278 to - 0.057) and standard deviations close to one (1.001 to 1.128); additionally, 6.0% (95% confidence interval (CI) 3.1-8.9%) and 6.4% (95% CI 3.7-9.1%) of subjects were with observed data below LLN for FEV1/FVC in men and women, respectively. In contrast, for NE Asian equations, all mean values of z-FEV1 and z-FVC were smaller than - 0.5; for SE Asian equations, mean values of z-FEV1/FVC were significantly smaller than zero in men (- 0.333) and women (- 0.440). CONCLUSIONS: GLI-2012 equations for individuals of mixed ethnic origin adequately fitted spirometry data in this sample of Asian Americans. Future studies with larger sample sizes are needed to confirm these findings.

Spirometric instability - another hurdle in achieving real-world COPD diagnostic criteria?

Globally, mortality, morbidity and the economic burden of chronic obstructive pulmonary disease (COPD) are on the rise. In addition, its diagnosis continues to pose challenges to the physicians, which is compounded further by its new feature "spirometric instability." Based on the findings from the two recent observational studies, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommended repeat spirometry for the individuals with a fixed ratio between 0.6 and 0.8. In this perspective, we discuss the uncertainties and consequences of this critical update in the 2018 GOLD report.

Sigma Routing Metric for RPL Protocol.

This paper presents the adaptation of a specific metric for the RPL protocol in the objective function MRHOF. Among the functions standardized by IETF, we find OF0, which is based on the minimum hop count, as well as MRHOF, which is based on the Expected Transmission Count (ETX). However, when the network becomes denser or the number of nodes increases, both OF0 and MRHOF introduce long hops, which can generate a bottleneck that restricts the network. The adaptation is proposed to optimize both OFs through a new routing metric. To solve the above problem, the metrics of the minimum number of hops and the ETX are combined by designing a new routing metric called SIGMA-ETX, in which the best route is calculated using the standard deviation of ETX values between each node, as opposed to working with the ETX average along the route. This method ensures a better routing performance in dense sensor networks. The simulations are done through the Cooja simulator, based on the Contiki operating system. The simulations showed that the proposed optimization outperforms at a high margin in both OF0 and MRHOF, in terms of network latency, packet delivery ratio, lifetime, and power consumption.

Secure Service Proxy: A CoAP(s) Intermediary for a Securer and Smarter Web of Things.

As the IoT continues to grow over the coming years, resource-constrained devices and networks will see an increase in traffic as everything is connected in an open Web of Things. The performance- and function-enhancing features are difficult to provide in resource-constrained environments, but will gain importance if the WoT is to be scaled up successfully. For example, scalable open standards-based authentication and authorization will be important to manage access to the limited resources of constrained devices and networks. Additionally, features such as caching and virtualization may help further reduce the load on these constrained systems. This work presents the Secure Service Proxy (SSP): a constrained-network edge proxy with the goal of improving the performance and functionality of constrained RESTful environments. Our evaluations show that the proposed design reaches its goal by reducing the load on constrained devices while implementing a wide range of features as different adapters. Specifically, the results show that the SSP leads to significant savings in processing, network traffic, network delay and packet loss rates for constrained devices. As a result, the SSP helps to guarantee the proper operation of constrained networks as these networks form an ever-expanding Web of Things.

Prevalence and incidence of COPD in smokers and non-smokers: the Rotterdam Study.

COPD is the third leading cause of death in the world and its global burden is predicted to increase further. Even though the prevalence of COPD is well studied, only few studies examined the incidence of COPD in a prospective and standardized manner. In a prospective population-based cohort study (Rotterdam Study) enrolling subjects aged ≥45, COPD was diagnosed based on a pre-bronchodilator obstructive spirometry (FEV1/FVC < 0.70). In absence of an interpretable spirometry within the Rotterdam Study, cases were defined as having COPD diagnosed by a physician on the basis of clinical presentation and obstructive lung function measured by the general practitioner or respiratory physician. Incidence rates were calculated by dividing the number of incident cases by the total number of person years of subjects at risk. In this cohort of 14,619 participants, 1993 subjects with COPD were identified of whom 689 as prevalent ones and 1304 cases as incident ones. The overall incidence rate (IR) of COPD was 8.9/1000 person-years (PY); 95 % Confidence Interval (CI) 8.4-9.4. The IR was higher in males and in smokers. The proportion of female COPD participants without a history of smoking was 27.2 %, while this proportion was 7.3 % in males. The prevalence of COPD in the Rotterdam Study is 4.7 % and the overall incidence is approximately 9/1000 PY, with a higher incidence in males and in smokers. The proportion of never-smokers among female COPD cases is substantial.

Can an airway challenge test predict respiratory diseases? A population-based international study.

BACKGROUND: Evidence on the longitudinal association of airway responsiveness with respiratory diseases is scarce. The best indicator of responsiveness is still undetermined. OBJECTIVE: We investigated the association of airway responsiveness with the incidence of asthma, chronic obstructive pulmonary disease (COPD), and allergic rhinitis. METHODS: We studied 3851 subjects who underwent spirometry and methacholine challenge tests both at baseline (1991-1993), when they were 20 to 44 years old, and at follow-up (1999-2002) in the European Community Respiratory Health Survey. Airway responsiveness was defined based on the methacholine dose-response slope on both occasions. Incidence rate ratios for the association of airway responsiveness with disease occurrence were computed by using Poisson regression. RESULTS: With respect to reference (slope of the fourth quintile or greater), subjects with the greatest degree of airway responsiveness (slope less than the first quintile) showed the greatest risk of developing asthma, COPD, and allergic rhinitis (incidence rate ratios of 10.82, 5.53, and 4.84, respectively; all P < .01). A low slope predicted disease occurrence, even in subjects who did not reach a 20% decrease in FEV1 at the cumulative dose of 1 mg of methacholine (PD20 >1 mg). A decrease in slope over time was an independent predictor of disease risk. CONCLUSION: Airway responsiveness predicted new-onset asthma, COPD, and allergic rhinitis. Our study supports the use of a continuous noncensored indicator of airway responsiveness, such as the slope of the methacholine dose-response curve, in clinical practice and research because it showed clear advantages over PD20.

Outcome-based Definition of the Lower Limit of Normal in Spirometry: A Study of 26,000 Young Adult Men.

Rationale: The definition of the lower limit of normal (LLN) of spirometric variables is not well established. Objectives: To investigate the relationship between spirometric abnormalities defined with different thresholds of the LLN and clinical outcomes and to explore the possibility of using different LLN thresholds according to the pretest probability of disease. Methods: We studied the associations between prebronchodilator spirometric abnormalities (forced expiratory volume in the first second [FEV1] < LLN, forced vital capacity [FVC] < LLN, airflow obstruction, spirometric restriction) defined with different thresholds of the LLN (10th, 5th, 2.5th, 1st percentile) and multiple outcomes (prevalence of spirometric abnormalities, respiratory symptoms, all-cause and respiratory mortality) in 26,091 30- to 46-year-old men who participated in a general population survey in Norway in 1988-1990 and were followed for 26 years. Analyses were performed with both local and Global Lung Function Initiative (GLI)-2012 reference equations, stratified by pretest risk (presence or absence of respiratory symptoms), and adjusted for age, body mass index, smoking, and education. Results: In the total population, the prevalence of airflow obstruction was 11.6% with GLI-LLN10, 11.0% with Local-LLN5, 6.1% with GLI-LLN5, 7.6% with Local-LLN2.5, and 3.5% with GLI-LLN2.5. The prevalence of spirometric restriction was 5.9% with GLI-LLN10, 5.2% with Local-LLN5, and 2.8% with GLI-LLN5. Increasingly lower thresholds of the LLN were associated with increasingly higher odds of respiratory symptoms and hazard of mortality for all spirometric abnormalities with both reference equations. Spirometric abnormalities defined with Local-LLN2.5 in asymptomatic subjects were associated with lower hazard of all-cause mortality (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.15-1.95 for FEV1 < LLN) than those defined with Local-LLN5 in the general population (HR, 1.67; 95% CI, 1.50-1.87 for FEV1 < LLN) and symptomatic subjects (HR, 1.67; 95% CI, 1.46-1.91 for FEV1 < LLN). Overall, the prevalence of spirometric abnormalities and associations with outcomes obtained with Local-LLN5 were comparable to those obtained with GLI-LLN10 and those obtained with Local-LLN2.5 to GLI-LLN5. Conclusions: There is a relationship between statistically based thresholds of the LLN of spirometric variables and clinical outcomes. Different thresholds of the LLN may be used in different risk subgroups of subjects, but the choice of the threshold needs to be evaluated together with the choice of reference equations.

COPD in Never-Smokers: BOLD Australia Study.

Purpose: Tobacco smoking is the major risk factor for COPD, and it is common for other risk factors in never-smokers to be overlooked. We examined the prevalence of COPD among never-smokers in Australia and identified associated risk factors. Methods: We used data from the Australia Burden of Obstructive Lung Disease (BOLD) study, a cross-section of people aged ≥40 years from six sites. Participants completed interviews and post-bronchodilator spirometry. COPD was primarily defined as an FEV1/FVC ratio <0.70 and secondarily as the ratio less than the lower limit of normal (LLN). Results: The prevalence of COPD in the 1656 never-smokers who completed the study was 10.5% (95% CI: 9.1-12.1%) [ratio

Comparison of the lower limit of normal to the fixed ratio method for the diagnosis of airflow obstruction at high altitudes: a large cross-sectional survey of subjects living between 3000-4700 m above sea level.

BACKGROUND: There is no general agreement on the preferential use of a fixed ratio (FR) of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) < 0.7 vs. the lower limit of normal (LLN) of FEV1/FVC to define airflow obstruction. Determining the impact of these different cut-off levels in people living at high altitudes has not been studied. We assessed the prevalence of airflow obstruction and its clinical characteristics in residents living at high altitude using a fixed ratio and the LLN of FEV1/FVC according to Global Lung Initiative 2012 (GLI) reference values. METHODS: Using a multistage stratified sampling method, 3702 participants (aged ≥ 15 years) living at an altitude of 3000-4700 m in Tibet were included. RESULTS: 11.4% and 7.7% of participants had airflow obstruction according to GLI-LLN and a fixed FEV1/FVC cut-off value, respectively. The participants in the FR-/LLN+ group were younger, predominantly female, more frequently exposed to household air pollution, and had a higher proportion of chronic obstructive pulmonary disease assessment test scores ≥ 10 than those in the FR-/LLN- group. They also had a significantly lower FEV1 and a higher frequency of small airway dysfunction. Compared with the participants of the FR+/LLN+ group, those in the FR-/LLN+ group showed no significant difference in the risk factors for airflow obstruction and respiratory symptoms, but had a lower prevalence of small airway dysfunction. CONCLUSIONS: Defining airflow obstruction according to LLN, instead of using an FR, identified younger individuals with more frequent clinical symptoms of airflow obstruction and small airway dysfunction.

A case report of the transanal lateral lymph node dissection with a combined abdominal assisted approach for the lower rectal cancer.

INTRODUCTION: Low and mid rectal cancer cells have the tendency to spread in the lateral pelvic lymph node (LPLN). The Japanese guidelines recommend systematic lymph node dissection when a positive LPLN is suspected or in stages II-III rectal cancer. However, laparoscopic lymph node dissection is complex and challenging. We introduce transanal LPLN dissection using an abdominal approach. PRESENTATION OF CASE: A 78-year-old man was diagnosed with advanced rectal cancer. Computed tomography and magnetic resonance imaging showed lower rectal wall thickening and bilateral lateral lymph node swelling. We performed laparoscopic abdominal peritoneal resection with combined bilateral LPLN dissection using abdominal and transanal approaches. He had an uneventful postoperative course with no signs of recurrence at the 5-month follow-up. DISCUSSION: LPLN metastases for low rectal cancer especially occur at the bottom of the deep pelvic spaces. As laparoscopic LPLND for low rectal cancer can be complicated, we adopted abdominal and transanal approaches, which provide the advantage of an anatomical view. This procedure may improve lateral pelvic anatomical structure viewing, and may offer advantages over laparoscopic abdominal approaches for visualizing and dissecting LPLNs. CONCLUSION: Curative resection has become available for rectal cancer with transanal LPLN dissection. LPLN dissection with combined abdominal and transanal approaches is a feasible treatment for advanced rectal cancer.

Prevalence and characteristics of chronic obstructive pulmonary disease in China with a diagnostic criterion of FEV1/FVC less than the lower limit of normal-a reanalysis of Chinese epidemiological survey of COPD (CESCOPD) study.

Background: To reappraise the prevalence and characteristics of chronic obstructive pulmonary disease (COPD) in China with a criterion of FEV1/FVC < the lower limit of normal (LLN). Methods: We assessed the incidence and characteristics of airflow limitation using data from the Chinese Epidemiological Survey of COPD study-a multicenter, randomized trial, with an age-dependent LLN reference equation [established by the Guangzhou Institute of Respiratory Health (GIRH)]. Questionnaire and spirometry data were collected for all eligible subjects. COPD prevalence, risk factors, severity distribution, as well as comparisons of characteristics between the LLN and 0.7 were analyzed. Results: COPD prevalence was 9.0% among participants aged 40-80 years in China with the criterion of LLN. Greater prevalence was observed in female sex, rural areas and never smokers than with the GOLD 0.7 fixed ratio. Age distribution showed a higher incidence of COPD in people under 60 years but lower in participants over 60 years of age. With the LLN FEV1 reference equation, patients in stage I were decreased (15.8% vs. 24.6%, P<0.001), while the proportion of patients in stage III and IV were increased when compared with the China 2002 revised equation (27.7% vs. 21.1%, for stage III, P<0.001; 8.7% vs. 5.6% for stage IV, P=0.001). Only 30.8% of patients with COPD had ever been "diagnosed" with COPD and 60.6% of the patients had respiratory symptoms, both lower than that under the GOLD 0.7 fixed-ratio criterion (35.5%, P=0.004; 64.8% for symptoms, P=0.014). Conclusions: With the GIRH-LLN criterion, COPD prevalence was slightly higher, and a large number of women, rural patients and nonsmokers with young age and little symptoms were diagnosed when compared with GOLD 0.7 fixed ratio. These subjects may, therefore, deserve further attention and may warrant regular follow-up. Trial Registration: Registration number: ChiCTR-ECS-13004110.

Obeticholic acid is associated with improvements in AST-to-platelet ratio index and GLOBE score in patients with primary biliary cholangitis.

BACKGROUND & AIMS: Biochemical markers, including GLOBE score and aspartate aminotransferase-to-platelet ratio index (APRI), are used to stratify risk in patients with primary biliary cholangitis (PBC). This study aimed to evaluate the effects of obeticholic acid (OCA) on categorical shifts in GLOBE score, APRI, and both combined, based on data from POISE, a phase III placebo-controlled trial in patients with PBC who had an incomplete response or were intolerant to ursodeoxycholic acid. METHODS: In a post hoc analysis, baseline and Month 12 data from POISE were used to calculate the APRI and GLOBE score. Patients were stratified into 3 risk groups based on a combination of APRI (0.54) and GLOBE (0.3 or age-specific) thresholds. RESULTS: The analysis included 215 patients (47 low risk; 79 moderate risk; 89 high risk). Using the combined GLOBE score (threshold of 0.3) and APRI thresholds, there was improvement in ≥1 risk stage in 37% and 35% of patients in the OCA 5-10 mg and 10 mg groups, respectively, vs. 12% in the placebo group (both p <0.05). Progression occurred in 10% and 0% in the 5-10 mg and 10 mg groups vs. 37% in the placebo group. Results with GLOBE age-specific thresholds were similar. CONCLUSIONS: Based on change in APRI and GLOBE score at 12 months, OCA treatment is associated with reduction in the predicted risk of liver-related complications in patients with PBC. LAY SUMMARY: Primary biliary cholangitis (PBC) is a chronic disease affecting the liver. People who suffer from PBC are at risk of serious long-term complications. Information from certain blood tests can be used to estimate the likelihood of experiencing long-term complications. The results of this study showed that based on blood test results, people taking obeticholic acid, with or without ursodeoxycholic acid, for PBC were predicted to have a better outcome than those taking placebo. CLINICAL TRIALS REGISTRATION: NCT01473524.

Histological activity despite normal ALT and IgG serum levels in patients with autoimmune hepatitis and cirrhosis.

BACKGROUND & AIMS: In autoimmune hepatitis (AIH), normal levels of transaminases and IgG define biochemical remission and are considered the best surrogate markers for histological remission. This study assessed whether this also applies to patients with AIH cirrhosis. METHODS: In this European multicentric study, we included 125 biopsies from 113 patients with AIH and histologically proven cirrhosis; 105 biopsies from 104 patients with AIH without cirrhosis served as controls. Biochemical parameters were available within 4 weeks of biopsy. AIH activity was graded according to the modified Hepatitis Activity Index (mHAI), with mHAI ≥4/18 considered to indicate risk of disease progression. RESULTS: In total, 47 out of 125 liver biopsies were obtained from patients with AIH cirrhosis and normal ALT levels at time of biopsy. Only 26% (12/47) of those livers showed histological remission (mHAI <4/18), whereas 36% (17/47) showed moderate to high histological activity (mHAI ≥6/18). In patients with noncirrhotic AIH, 88% (46/52 biopsies) of cases with normal ALT levels had histological remission and only 4% (2/52) had an mHAI ≥6/18 (p <0.001). The addition of IgG to define complete biochemical remission only slightly improved the association with histological remission in the limited number of patients with AIH cirrhosis available for analysis [29% (5/17) of biopsies with mHAI <4/18]. ALT correlated closely with mHAI in AIH without cirrhosis but poorly in AIH with cirrhosis. CONCLUSIONS: In contrast to patients with noncirrhotic AIH, in patients with AIH cirrhosis, who are at risk of disease progression, normal ALT levels and potentially also complete biochemical remission are poor surrogate markers of histological remission. Thus, new biomarkers are needed to monitor disease activity and progression in patients with AIH cirrhosis. LAY SUMMARY: Autoimmune hepatitis (AIH) is an inflammatory disease of the liver that usually responds to immunosuppressive therapy. Serum transaminases and IgG levels within the normal ranges define complete biochemical remission and are considered as surrogate markers for histological disease activity. Here, we show that those biochemical markers are not sufficient to indicate low disease activity in patients with AIH and already established cirrhosis. Consequently, until better biomarkers for disease activity are found, only liver biopsy can reliably indicate disease activity in the presence of cirrhosis. Additional investigations, such as measurements of liver stiffness, should be undertaken to monitor non-invasively for disease progression in patients with AIH and established cirrhosis.

Impacts of Different Spirometry Reference Equations and Diagnostic Criteria on the Frequency of Airway Obstruction in Adult People of North China.

Background and Objective: The reference equations and diagnostic criteria play a critical role in the interpretation of pulmonary function tests (PFTs). The aim was to investigate the impacts of different reference equations and diagnostic criteria on the frequency of airway obstruction in adult people of a large teaching hospital of North China. Methods: The spirometry data of all adult people who underwent PFTs in Qilu hospital from April 2012 to November 2015 were collected. Two spirometry reference equations, namely, Zhongshan-2011 and Global Lung Function Initiative 2012 (GLI-2012) were compared. The frequency of airway obstruction using different spirometry prediction equations and diagnostic criteria including forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <92% of predicted value and FEV1/FVC 

Determining the thresholds for abnormal left ventricular strains in healthy subjects by echocardiography: a meta-analysis.

BACKGROUND: Left ventricular global longitudinal strain (LVGLS), circumferential strain (LVGCS) and radial strain (LVGRS) are echocardiographic parameters with wide clinical applicability. However, the thresholds for abnormal left ventricular (LV) strains, particularly the lower limits of normal (LLN), are not well established. This meta-analysis determined the mean and LLN of two- (2D) and three-dimensional (3D) LV strain in healthy subjects and factors that influence strain measurements. METHODS: We searched PubMed, Embase and Cochrane databases until 31 December 2019 for studies reporting left ventricular (LV) global strain in at least 50 healthy subjects. We pooled means and LLNs of 2D and 3D LV strain using random-effects models, and performed subgroup and meta-regression analysis for LVGLS. RESULTS: Forty-four studies were eligible totaling 8,910 subjects. The pooled means and LLNs (95% confidence intervals) were -20.1% (-20.7%, -19.6%) and -15.4% (-16.0%, -14.7%) respectively for 2D-LVGLS; -21.9% (-23.4%, -20.3%) and -15.3% (-16.9%, -13.8%) respectively for 2D-LVGCS; and 48.4% (43.8%, 53.0%) and 25.5% (17.8%, 33.1%) respectively for 2D-LVGRS. All pooled analyses demonstrated significant heterogeneity, and means and LLNs of and 3D-LV strains differed marginally from 2D. Only vendor software was associated with differences in pooled means and LLN of 2D-LVGLS. CONCLUSIONS: In conclusion, pooled means and LLNs of 2D- and 3D-LV global strain parameters in healthy subjects were reported. Based on the pooled LLNs, thresholds for abnormal, borderline and normal strains can be defined, such as less negative than -14.7%, between -14.7% and -16.0% and more negative than -16.0% respectively for 2D-LVGLS, and 2D-LVGLS values are only affected by vendor software.

Reference equations for spirometry in healthy Asian children aged 5 to 18 years in Taiwan.

BACKGROUND AND OBJECTIVE: This study aimed to establish reference equations for spirometry in healthy Taiwanese children and assess the applicability of the Global Lung Function Initiative (GLI)-2012 equations to Taiwanese children. METHODS: Spirometric data collected from 757 healthy Taiwanese children aged 5 to 18 years in a population-based cohort study. Prediction equations derived using linear regression and the generalized additive models for location, scale and shape (GAMLSS) method, respectively. RESULTS: The GLI-2012 South East Asian equations did not provide a close fit with mean ± standard error z-scores of -0.679 ± 0.030 (FVC), -0.186 ± 0.044 (FEV1), -0.875 ± 0.049 (FEV1/FVC ratio) and -2.189 ± 0.063 (FEF25-75) for girls; and 0.238 ± 0.059, -0.061 ± 0.053, -0.513 ± 0.059 and -1.896 ± 0.077 for boys. The proposed GAMLSS models took age, height, and weight into account. GAMLSS models for boys and girls captured the characteristics of spirometric data in the study population closely in contrast to the linear regression models and the GLI-2012 equations. CONCLUSION: This study provides up-to-date reference values for spirometry using GAMLSS modeling in healthy Taiwanese children aged 5 to 18 years. Our study provides evidence that the GLI-2012 reference equations are not properly matched to spirometric data in a contemporary Taiwanese child population, indicating the urgent need for an update of GLI reference values by inclusion of more data of non-Caucasian decent.