A combined approach to generate laboratory reference intervals using unbalanced longitudinal data

AbstractBackground:The interpretation of individual laboratory test results requires the availability of population-based reference intervals. In children, reference interval estimation has to consider frequently the strong age-dependency. Generally, for the construction of reference intervals, a sufficiently large number of independent measurement values is required. Data selections from hospitals or cohort studies often comprise dependencies violating the independence assumption.Methods:In this article, we propose a combination of LMS-like (mean, M; coefficient of variation, S; skewness, λ or L) and resampling methods to overcome this drawback. The former is recommended by the World Health Organization (WHO) for the construction of continuous reference intervals of anthropometric measurements in children. The approach allows the inclusion of dependent measurements, for example, repeated measurements per subject. It also provides pointwise confidence envelopes as a measure of reliability.Results and conclusions:The combination of LMS-type methods and resampling provides a feasible approach to estimate age-dependent percentiles and reference intervals using unbalanced longitudinal data.

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Triage Management, Survival, and the Law in the Age of Ebola

Disaster Medicine and Public Health Preparedness ◽

10.1017/dmp.2014.117 ◽

2014 ◽

Vol 9 (1) ◽

pp. 38-43 ◽

Cited By ~ 12

Author(s):

Frederick M Burkle ◽

Christopher M Burkle

Keyword(s):

Public Health ◽

International Health ◽

Epidemiological Data ◽

Population Based ◽

World Health ◽

Economic Stability ◽

Budget Cuts ◽

The Public ◽

Level 3 ◽

Health Organization

AbstractLiberia, Sierra Leone, and Guinea lack the public health infrastructure, economic stability, and overall governance to stem the spread of Ebola. Even with robust outside assistance, the epidemiological data have not improved. Vital resource management is haphazard and left to the discretion of individual Ebola treatment units. Only recently has the International Health Regulations (IHR) and World Health Organization (WHO) declared Ebola a Public Health Emergency of International Concern, making this crisis their fifth ongoing level 3 emergency. In particular, the WHO has been severely compromised by post-2003 severe acute respiratory syndrome (SARS) staffing, budget cuts, a weakened IHR treaty, and no unambiguous legal mandate. Population-based triage management under a central authority is indicated to control the transmission and ensure fair and decisive resource allocation across all triage categories. The shared responsibilities critical to global health solutions must be realized and the rightful attention, sustained resources, and properly placed legal authority be assured within the WHO, the IHR, and the vulnerable nations. (Disaster Med Public Health Preparedness. 2014;0:1-6)

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Leading causes of blindness and visual impairment in the region of Eastern Herzegovina

Medicinski pregled ◽

10.2298/mpns0602015c ◽

2006 ◽

Vol 59 (1-2) ◽

pp. 15-18 ◽

Cited By ~ 1

Author(s):

Lala Ceklic ◽

Slobodanka Latinovic ◽

Petar Aleksic

Keyword(s):

Visual Impairment ◽

Visually Impaired ◽

Age Distribution ◽

Epidemiological Studies ◽

Population Based ◽

World Health ◽

Visual Disability ◽

Common Causes ◽

Health Organization ◽

Blind Persons

Introduction. Visual impairment and blindness are serious social and health problems in the world. 1992 classification of visual disorders by World Health Organization has recently been implemented. The goal of this study was to determine common causes of visual impairment and blindness in the region of Eastern Herzegovina. Material and methods. In this population based study we have analyzed medical records stored in the regional Association of Visually Impaired and Blind Persons of the Republic of Srpska (Trebinje, Bileca, Foca, Eastern Sarajevo). The analysis included sex and age distribution of registered population, classification and leading causes of visual disability and blindness. Results. There are 298 registered persons with visual disability and blindness in the region of Eastern Herzegovina and Eastern Sarajevo. The prevalence of visual impairment and blindness in the aforementioned region is 0.1%. Among the studied population, there are more males than females with visual disability or blindness (56% versus 44%). Most (78%) of registered persons are blind, and only 22% are visually impaired. 43% of registered population are in the IV category and only 8.38% are registered in the II category. Only 2% of registered population are children. Common causes of visual disability and blindness in the region of Eastern Herzegovina are: glaucoma (22%), cataract (17%), myopia alta (13%), diabetic retinopathy (12%) and ocular trauma (11%). Common causes of children's visual impairment include: optic nerve anomalies, congenital cataract and premature retinopathy. Discussion and conclusion Compared with literature data, common causes of blindness and visual impairment in the region of Eastern Herzegovina do not differ significantly from those in other regions. Registration is based on the WHO model, but it is possible only by performing active epidemiological studies. .

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Trajectories and Determinants of Physical Activity during COVID-19 Pandemic: A Population-Based Study of Middle-Aged and Elderly Individuals in The Netherlands

Nutrients ◽

10.3390/nu13113832 ◽

2021 ◽

Vol 13 (11) ◽

pp. 3832

Author(s):

Amy Hofman ◽

Marlou A. M. Limpens ◽

Tosca O. E. de Crom ◽

Mohammad Arfan Ikram ◽

Annemarie I. Luik ◽

...

Keyword(s):

Physical Activity ◽

The Netherlands ◽

Latent Class ◽

Multinomial Logistic Regression ◽

Public Health Problem ◽

Population Based ◽

World Health ◽

Major Public Health Problem ◽

Middle Aged ◽

Health Organization

Physical inactivity is a major public health problem, and there are concerns this might have increased during the COVID-19 pandemic. We aimed to identify distinct trajectories of physical activity over a 6-week period after the first restrictive measures and to explore determinants of these trajectories in a population-based cohort of middle-aged and elderly in the Netherlands (n = 5777). We observed that at least 59% of participants did not meet the World Health Organization recommendations for physical activity. Using latent class trajectory analyses over three time points, we identified five distinct trajectories, including four steady trajectories at different levels (very low, low, medium and high) and one increasing trajectory. Using multinomial logistic regression analyses, we observed that, compared to the ‘steadily high’ trajectory, participants in the ‘steadily very low’ trajectory were more often older, lower educated, reporting poorer physical health, more depressive symptoms, consuming a less healthy diet, smoking, and lower alcohol use, and were less often retired. A similar pattern of determinants was seen for those in the increasing trajectory, albeit with smaller effect sizes. Concluding, we observed low levels of physical activity that generally remained during the pandemic. The determinants we described can help identify groups that require additional preventive interventions.

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Distribution of HOMA-IR in a population-based cohort and proposal for reference intervals

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2021-0643 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Bassel Matli ◽

Andreas Schulz ◽

Thomas Koeck ◽

Tanja Falter ◽

Johannes Lotz ◽

...

Keyword(s):

Insulin Resistance ◽

Fasting Glucose ◽

Reference Group ◽

Reference Interval ◽

Population Based ◽

Reference Intervals ◽

Health Study ◽

Specific Reference ◽

Model Assessment ◽

Significant Difference

Abstract Objectives Insulin resistance (IR) is a hallmark of type 2 diabetes mellitus (DM). The homeostatic model assessment of insulin resistance (HOMA-IR) provides an estimate for IR from fasting glucose and insulin serum concentrations. The aim of this study was to obtain a reference interval for HOMA-IR for a specific insulin immunoassay. Methods The Gutenberg Health Study (GHS) is a population-based, prospective, single-center cohort study in Germany with 15,030 participants aged 35–74 years. Fasting glucose, insulin, and C-peptide were available in 10,340 participants. HOMA-IR was calculated in this group and three reference subgroups with increasingly more stringent inclusion criteria. Age- and sex-dependent distributions of HOMA-IR and reference intervals were obtained. In a substudy three insulin assays were compared and HOMA-IR estimated for each assay. Results Among the 10,340 participants analyzed there were 6,590 non-diabetic, 2,901 prediabetic, and 849 diabetic individuals. Median (interquartile range [IQR]) HOMA-IR was 1.54 (1.13/2.19), 2.00 (1.39/2.99), and 4.00 (2.52/6.51), respectively. The most stringently selected reference group consisted of 1,065 persons. Median (IQR) HOMA-IR was 1.09 (0.85/1.42) with no significant difference between men and women. The 97.5th percentile was 2.35. There was a non-significant trend towards higher values with older age. Comparison of three immunoassays for insulin showed an unsatisfactory correlation among the assays and systematic differences in calculated HOMA-IR. Conclusions We present HOMA-IR reference intervals for adults derived by more or less stringent selection criteria for the reference cohort. In addition we show that assay specific reference intervals for HOMA-IR are required.

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Population-Based Estimation of Dental Caries and Periodontal Disease Rates of Gravid and Recently Postpartum Women in Lilongwe, Malawi

American Journal of Perinatology Reports ◽

10.1055/s-0039-1695003 ◽

2019 ◽

Vol 09 (03) ◽

pp. e268-e274

Author(s):

Kathleen M. Antony ◽

Peter N. Kazembe ◽

Ryan M. Pace ◽

Judy Levison ◽

Jesse Mlotha-Namarika ◽

...

Keyword(s):

Dental Caries ◽

Periodontal Disease ◽

Health Workers ◽

Population Based ◽

Oral Health Status ◽

World Health ◽

Postpartum Women ◽

Dental Disease ◽

Dmf Index ◽

Health Organization

Objectives The objective of this study was to determine the rate of dental caries and periodontal disease among gravid and recently postpartum women at five delivery centers within and surrounding Lilongwe, Malawi. Study Design We partnered with obstetric specialists, community health workers, and dentists to perform dental history interviews and dental examinations during the study period from December 2012 to May 2014. Dental examinations were performed according to World Health Organization standards to assess periodontal and oral health status. Results Among the 387 gravid and recently postpartum women, the rate of dental caries was 69.3% and the rate of composite dental disease (caries and periodontal disease) was 76.7%. The majority (69.5%) of women examined had a decayed-missing-filled (DMF) index greater than or equal to one; the average DMF Index was 2.48. The majority of women had never seen a dentist (62.8%). However, most did perform oral hygiene, two or more times per day (90.2%); most women reported brushing with toothpaste (88.1%). Conclusion When assessing this population for dental caries and periodontal disease, the rate of dental disease was high. Therefore, this may be an ideal setting to test for impactful interventions aimed at reducing caries and periodontal disease.

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Personalized Reference Intervals in Laboratory Medicine: A New Model Based on Within-Subject Biological Variation

Clinical Chemistry ◽

10.1093/clinchem/hvaa233 ◽

2020 ◽

Author(s):

Abdurrahman Coşkun ◽

Sverre Sandberg ◽

Ibrahim Unsal ◽

Coskun Cavusoglu ◽

Mustafa Serteser ◽

...

Keyword(s):

Steady State ◽

Personalized Medicine ◽

Clinical Chemistry ◽

Reference Interval ◽

Reference Intervals ◽

Biological Variation ◽

Test Results ◽

Steady State Condition ◽

Laboratory Test Results ◽

Measurement Results

Abstract Background The concept of personalized medicine has received widespread attention in the last decade. However, personalized medicine depends on correct diagnosis and monitoring of patients, for which personalized reference intervals for laboratory tests may be beneficial. In this study, we propose a simple model to generate personalized reference intervals based on historical, previously analyzed results, and data on analytical and within-subject biological variation. Methods A model using estimates of analytical and within-subject biological variation and previous test results was developed. We modeled the effect of adding an increasing number of measurement results on the estimation of the personal reference interval. We then used laboratory test results from 784 adult patients (>18 years) considered to be in a steady-state condition to calculate personalized reference intervals for 27 commonly requested clinical chemistry and hematology measurands. Results Increasing the number of measurements had little impact on the total variation around the true homeostatic set point and using ≥3 previous measurement results delivered robust personalized reference intervals. The personalized reference intervals of the study participants were different from one another and, as expected, located within the common reference interval. However, in general they made up only a small proportion of the population-based reference interval. Conclusions Our study shows that, if using results from patients in steady state, only a few previous test results and reliable estimates of within-subject biological variation are required to calculate personalized reference intervals. This may be highly valuable for diagnosing patients as well as for follow-up and treatment.

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Significance of Abuse Chemical Contamination of Returnable Dairy Containers: Hazard Assessment

Journal of Food Protection ◽

10.4315/0362-028x-41.12.965 ◽

1978 ◽

Vol 41 (12) ◽

pp. 965-973 ◽

Cited By ~ 3

Author(s):

JOHN M. GASAWAY

Keyword(s):

Hazard Assessment ◽

Pesticide Residues ◽

Daily Intake ◽

World Health ◽

Test Results ◽

Chemical Contamination ◽

Laboratory Findings ◽

Laboratory Test Results ◽

Health Organization ◽

Water Contents

Certain pesticide residues reabsorbed into milk (or water) contents when stored in LEXAN® resin and polyethylene plastic returnable milk containers that had been exposed to diluted pesticide products, washed, and subsequently filled. The significance of these laboratory test results is comprehensively discussed by attempting to characterize the nature of exposure to pesticide residues from a washed returnable dairy container, as opposed to exposure to milk containing pesticide residues of non-container origin. Laboratory findings are compared to actual public use experience with returnable plastic dairy containers. A hazard assessment is presented, which includes a comparison of quantities of pesticide residues found extracting with existing Federal milk tolerance standards, food tolerance standards, unavoidable contaminant food additive regulations, World Health Organization and Safe Drinking Water Committee acceptable daily intake values. The probability of purchase of milk that is contaminated with pesticide residues, where the washed returnable dairy container is the source, is presented.

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Evaluating Percentage-Based Reporting of Glucose-6-Phosphate Dehydrogenase (G6PD) Enzymatic Activity in a National Reference Laboratory: Assessment of Patient Eligibility for Plasmodium vivax Radical Cure Therapy

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqz116.005 ◽

2019 ◽

Vol 152 (Supplement_1) ◽

pp. S82-S82

Author(s):

Emilia Calvaresi ◽

Jonathan Genzen

Keyword(s):

Normal Activity ◽

Population Based ◽

G6pd Activity ◽

World Health ◽

Reference Laboratory ◽

Data Sets ◽

Radical Cure ◽

Laboratory Assessment ◽

Data Set ◽

Health Organization

Abstract Objectives The World Health Organization recommends measurement of G6PD activity prior to initiation of 8-aminoquinolones for the treatment of P vivax malaria. An estimated 400 million people worldwide have G6PD deficiency, making them susceptible to hemolysis under oxidative stress. A new single-dose therapy (radical cure) for malaria with tafenoquine is contraindicated in patients with <70% normal G6PD activity due to its prolonged circulating half-life. However, most clinical laboratories report G6PD activity in units g/Hb or units/1012 RBC and do not provide percentage of normal activity, making potential eligibility determination challenging. Methods Using an IRB-exempt protocol, a limited data set of consecutive G6PD quantitative results was retrieved from the clinical laboratory’s enterprise data warehouse. Laboratory testing of these specimens was previously performed at 37°C using an automated enzymatic assay (Pointe Scientific) configured on a cobas c501 chemistry analyzer (Roche Diagnostics). Data were assembled to include adults age 18 to 89 years and excluded repeat results from the same patients as well as outliers. Conclusion The final data set included 52,216 results (female, 55.9%, n = 29,173; male, 44.1%, n = 23,043) from 47 US states. An adjusted male median (100% G6PD activity) was derived using an approach proposed by the Bangkok Workshop guidelines (Domingo et al., Malaria Journal, 2013), modified to more accurately differentiate bimodal peaks in population G6PD histograms. The laboratory-specific, adjusted male median was 12.7 U g/Hb and was similar to peak values derived from alternative curve-fitting approaches. Applying this median to gender-specific data sets, 5.4% of males and 3.8% of females were found to have <70% of normal activity (<8.9 U g/Hb). This study demonstrates the feasibility of percentage-based G6PD result reporting in adults; further studies will query percentage-based reporting in pediatric populations. Population-based medians will vary based on G6PD assay type and temperature and should be established by laboratories prior to percentage-based reporting.

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Incidence of Acute Ischemic Stroke With Visible Arterial Occlusion

Stroke ◽

10.1161/strokeaha.120.029949 ◽

2020 ◽

Vol 51 (7) ◽

pp. 2122-2130 ◽

Cited By ~ 1

Author(s):

Gauthier Duloquin ◽

Mathilde Graber ◽

Lucie Garnier ◽

Valentin Crespy ◽

Pierre-Olivier Comby ◽

...

Keyword(s):

Arterial Occlusion ◽

Population Based ◽

Annual Incidence ◽

World Health ◽

Annual Incidence Rate ◽

Anterior Circulation ◽

The World ◽

Health Organization ◽

Proximal Occlusion ◽

Population Based Registry

Background and Purpose: Because of several methodological limitations, previous studies focusing on the prevalence of large vessel occlusion in ischemic stroke (IS) patients provided conflicting results. We evaluated the incidence of IS with a visible arterial occlusion using a comprehensive population-based registry. Methods: Patients with acute IS were prospectively identified among residents of Dijon, France, using a population-based registry (2013–2017). All arterial imaging exams were reviewed to assess arterial occlusion. Annual incidence rates of IS (first-ever and recurrent events) and IS with a visible occlusion were calculated. Results: One thousand sixty cases of IS were recorded (mean age: 76.0±15.8 years, 53.9% women). Information about arterial imaging was available in 971 (91.6%) of them, and only preexisting dementia was independently associated with having missing information (odds ratio=0.34 [95% CI, 0.18–0.65], P =0.001). Among these patients, 284 (29.2%) had a visible arterial occlusion. Occlusion site was the anterior circulation in 226 patients (23.3% of overall patients with available data) and the posterior circulation in 58 patients (6.0%). A proximal occlusion of the anterior circulation was observed in 167 patients (17.2%). The crude annual incidence rate of total IS per 100 000 was 138 (95% CI, 129–146). Corresponding standardized rates were 66 (95% CI, 50–82) to the World Health Organization and 141 (95% CI, 118–164) to the 2013 European populations. The crude annual incidence rate of IS with a visible arterial occlusion per 100 000 was 37 (95% CI, 33–41) and that of IS with a proximal occlusion of the anterior circulation was 22 (95% CI, 18–25). Corresponding standardized rates were 18 (95% CI, 10–26) and 10 (95% CI, 8–13) to the World Health Organization population, and 38 (95% CI, 26–50) and 23 (95% CI, 19–26) to the 2013 European population, respectively. Conclusions: These results will be helpful to plan the need for thrombectomy-capable stroke center resources.

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