Validation of Instrument Measuring Continuous Variable in Medicine

In medicine, accurate measurement of clinical values is vital, either at the stage of health screening, diagnosing cases or making prognosis. There are numerous instruments or machines that have been invented for the purpose of measuring various clinical variables such as blood pressure, glucose level, body temperature and oxygen level. When a new method of measurement or instrument is invented, the quality of the instrument has to be assessed. This chapter will focus on the application of statistical methods used to analyse continuous data in a method comparison study or validation study in medicine. The concept of validity and analysis in method comparison study will be discussed. This chapter also reviews the theoretical aspects of several common methods and approaches that have been used to measure agreement and reliability including the Bland-Altman limits of agreement (LoA) and intra-class correlation coefficient (ICC). Issues related to method comparison studies will be highlighted, which include the evaluation of agreement and reliability in a single study, the application of multiple statistical methods and the use of inappropriate methods in testing agreement and reliability. Finally, the importance of education in method comparison studies among medical professional will be emphasized

Clinical Symptoms of Arboviruses in Mexico

Arboviruses such as Chikungunya (CHIKV), Dengue (DENV), and Zika virus (ZIKV) have emerged as a significant public health concern in Mexico. The existing literature lacks evidence regarding the dispersion of arboviruses, thereby limiting public health policy’s ability to integrate the diagnosis, management, and prevention. This study seeks to reveal the clinical symptoms of CHIK, DENV, and ZIKV by age group, region, sex, and time across Mexico. The confirmed cases of CHIKV, DENV, and ZIKV were compiled from January 2012 to March 2020. Demographic characteristics analyzed significant clinical symptoms of confirmed cases. Multinomial logistic regression was used to assess the association between clinical symptoms and geographical regions. Females and individuals aged 15 and older had higher rates of reported significant symptoms across all three arboviruses. DENV showed a temporal variation of symptoms by regions 3 and 5, whereas ZIKV presented temporal variables in regions 2 and 4. This study revealed unique and overlapping symptoms between CHIKV, DENV, and ZIKV. However, the differentiation of CHIKV, DENV, and ZIKV is difficult, and diagnostic facilities are not available in rural areas. There is a need for adequately trained healthcare staff alongside well-equipped lab facilities, including hematological tests and imaging facilities

Dengue surveillance using gravid oviposition sticky (GOS) trap and dengue non-structural 1 (NS1) antigen test in Malaysia: Randomized controlled trial

Dengue remains a major public threat and existing dengue control/surveillance programs lack sensitivity and proactivity. More efficient methods are needed. A cluster randomized controlled trial was conducted for 18 months to determine the efficacy of using a combination of gravid oviposition sticky (GOS) traps and dengue non-structural 1 (NS1) antigen for early surveillance of dengue among Aedes mosquito. Eight residential apartments were randomly assigned into intervention and control groups. GOS traps were placed at the intervention apartments weekly to trap Aedes mosquitoes and these tested for dengue NS1 antigen. When dengue-positive pool was detected, the community were notified and advised to execute protective measures. Fewer dengue cases were recorded in the intervention group than the control. Detection of NS1-positive mosquitoes was significantly associated with GOS Aedes index ( rs = 0.68, P < 0.01) and occurrence of dengue cases ( rs = 0.31, P < 0.01). Participants’ knowledge, attitude, and practice (KAP) toward dengue control indicated significant improvement for knowledge (P < 0.01), practice (P < 0.01) and total scores (P < 0.01). Most respondents thought this surveillance method is good (81.2%) and supported its use nationwide. Thus, GOS trap and dengue NS1 antigen test can supplement the current dengue surveillance/control, in alignment with the advocated integrated vector management for reducing Aedes-borne diseases

Dengue surveillance using gravid oviposition sticky (GOS) trap and dengue non‑structural 1 (NS1) antigen test in Malaysia : randomized controlled trial

Dengue remains a major public threat and existing dengue control/surveillance programs lack sensitivity and proactivity. More efficient methods are needed. A cluster randomized controlled trial was conducted for 18 months to determine the efficacy of using a combination of gravid oviposition sticky (GOS) traps and dengue non-structural 1 (NS1) antigen for early surveillance of dengue among Aedes mosquito. Eight residential apartments were randomly assigned into intervention and control groups. GOS traps were placed at the intervention apartments weekly to trap Aedes mosquitoes and these tested for dengue NS1 antigen. When dengue-positive pool was detected, the community were notified and advised to execute protective measures. Fewer dengue cases were recorded in the intervention group than the control. Detection of NS1-positive mosquitoes was significantly associated with GOS Aedes index (rs = 0.68, P < 0.01) and occurrence of dengue cases (rs = 0.31, P < 0.01). Participants’ knowledge, attitude, and practice (KAP) toward dengue control indicated significant improvement for knowledge (P < 0.01), practice (P < 0.01) and total scores (P < 0.01). Most respondents thought this surveillance method is good (81.2%) and supported its use nationwide. Thus, GOS trap and dengue NS1 antigen test can supplement the current dengue surveillance/control, in alignment with the advocated integrated vector management for reducing Aedes-borne diseases

Statistical Methods Used to Test for Agreement of Medical Instruments Measuring Continuous Variables in Method Comparison Studies: A Systematic Review

BACKGROUND: Accurate values are a must in medicine. An important parameter in determining the quality of a medical instrument is agreement with a gold standard. Various statistical methods have been used to test for agreement. Some of these methods have been shown to be inappropriate. This can result in misleading conclusions about the validity of an instrument. The Bland-Altman method is the most popular method judging by the many citations of the article proposing this method. However, the number of citations does not necessarily mean that this method has been applied in agreement research. No previous study has been conducted to look into this. This is the first systematic review to identify statistical methods used to test for agreement of medical instruments. The proportion of various statistical methods found in this review will also reflect the proportion of medical instruments that have been validated using those particular methods in current clinical practice. METHODOLOGY/FINDINGS: Five electronic databases were searched between 2007 and 2009 to look for agreement studies. A total of 3,260 titles were initially identified. Only 412 titles were potentially related, and finally 210 fitted the inclusion criteria. The Bland-Altman method is the most popular method with 178 (85%) studies having used this method, followed by the correlation coefficient (27%) and means comparison (18%). Some of the inappropriate methods highlighted by Altman and Bland since the 1980s are still in use. CONCLUSIONS: This study finds that the Bland-Altman method is the most popular method used in agreement research. There are still inappropriate applications of statistical methods in some studies. It is important for a clinician or medical researcher to be aware of this issue because misleading conclusions from inappropriate analyses will jeopardize the quality of the evidence, which in turn will influence quality of care given to patients in the future

A Systematic Review of Statistical Methods Used to Test for Reliability of Medical Instruments Measuring Continuous Variables

Objective(s): Reliability measures precision or the extent to which test results can be replicated. This is the first ever systematic review to identify statistical methods used to measure reliability of equipment measuring continuous variables. This studyalso aims to highlight the inappropriate statistical method used in the reliability analysis and its implication in the medical practice.   Materials and Methods: In 2010, five electronic databases were searched between 2007 and 2009 to look for reliability studies. A total of 5,795 titles were initially identified. Only 282 titles were potentially related, and finally 42 fitted the inclusion criteria. Results: The Intra-class Correlation Coefficient (ICC) is the most popular method with 25 (60%) studies having used this method followed by the comparing means (8 or 19%). Out of 25 studies using the ICC, only 7 (28%) reported the confidence intervals and types of ICC used. Most studies (71%) also tested the agreement of instruments. Conclusion: This study finds that the Intra-class Correlation Coefficient is the most popular method used to assess the reliability of medical instruments measuring continuous outcomes. There are also inappropriate applications and interpretations of statistical methods in some studies. It is important for medical researchers to be aware of this issue, and be able to correctly perform analysis in reliability studies

The Determinants of Mental Health Literacy among Young Adolescents in Malaysia

Mental health literacy (MHL) is an established multifaceted concept that comprises mental health knowledge, help-seeking, and stigma. Adequate MHL (i.e., the ability to correctly recognize mental health disorders alongside having the intention to seek help) is able improve mental health outcomes among individuals. This study aims to examine the determinants of MHL among young Malaysian adolescents. A cross-sectional study was conducted among 1400 adolescents between 13 and 14 years old from nine national secondary schools in Selangor state, Malaysia. Sociodemographic determinants assessed included gender, age, ethnicity, smoking status, alcohol consumption, history of being bullied, feeling lonely, parental marital status, and parental income which were assessed using the Global School Based Student Health Survey. MHL was assessed using the Mental Health Literacy and Stigma questionnaire. Several factors were significantly associated with adequate levels of MHL following multivariate analysis, such as being female (AOR = 1.68; 95% CI 1.12, 2.52), older adolescents (AOR = 1.56; 95% CI 1.07, 2.30), not smoking (AOR = 1.99; 95% CI 1.20, 4.26), not consuming alcohol (AOR = 1.23; 95% CI 1.18, 2.41), and not feeling lonely (AOR = 1.25; 95% CI 1.06, 1.85). Addressing these determinants could be key in assisting the development of policies and programs to prevent mental health disorders among adolescents, which are currently on the rise

C-reactive protein/albumin ratio is a prognostic indicator for predicting surgical intervention and mortality in neonates with necrotizing enterocolitis

Purpose!#!The role of hypoalbuminemia and raised C-reactive protein (CRP) levels in predicting critical prognosis has been described extensively in adult literature. However, there are limited studies in pediatrics, particularly neonates. The CRP/albumin (CRP/ALB) ratio is often associated with higher mortality, organ failure and prolonged hospital stay. We hypothesized that the serum CRP/ALB ratio has a prognostic value in predicting surgery and mortality in neonates with necrotizing enterocolitis (NEC).!##!Methods!#!Retrospective review of all neonates with clinical and radiological evidence of non-perforated NEC that were treated in a tertiary-level referral hospital between 2009 and 2018. General patient demographics, laboratory parameters and outcomes were recorded. Receiver operating characteristics analysis was performed to evaluated optimal cut-offs and area under the curve (AUC) with 95% confidence intervals (CI).!##!Results!#!A total of 191 neonates were identified. Of these, 103 (53.9%) were born at ≤ 28 weeks of gestation and 101 (52.9%) had a birth weight of ≤ 1000 g. Eighty-four (44.0%) patients underwent surgical intervention for NEC. The overall survival rate was 161/191 (84.3%). A CRP/ALB ratio of ≥ 3 on day 2 of NEC diagnosis was associated with a statistically significant higher likelihood for surgery [AUC 0.71 (95% CI 0.63-0.79); p &amp;lt; 0.0001] and mortality [AUC 0.66 (95% CI 0.54-0.77); p = 0.0150], respectively.!##!Conclusions!#!A CRP/ALB ratio of ≥ 3 on day 2 is indicative of a critical pathway in neonates with radiologically confirmed, non-perforated NEC. This could be used as an additional criterion to guide parental counselling in NEC for surgical intervention and mortality

Data sets to demonstrate the inappropriate use of correlation coefficient in testing agreement.

<p>Data sets to demonstrate the inappropriate use of correlation coefficient in testing agreement.</p

Assessing inter-subject variability in cerebral blood flow control measurements

The aim of this study is to assess inter-individual variability and repeatability in measures assessing blood flow control in the brain during spontaneous and enhanced fluctuations in blood pressure. There is clear evidence of inter-individual difference during enhanced blood pressure variability, but not at rest. This difference exceeds the within-individual variability by factor of 2.73