Algorithm on age partitioning for estimation of reference intervals using clinical laboratory database exemplified with plasma creatinine

A preliminary study on the reference intervals of serum tumor marker in apparently healthy elderly population in southwestern China using real-world data

BACKGROUND

The aim is to establish and verify reference intervals (RIs) for serum tumor markers for an apparently healthy elderly population in Southwestern China using an indirect method.

METHODS

Data from 35,635 apparently healthy elderly individuals aged 60 years and above were obtained in West China Hospital from April 2020 to December 2021. We utilized the Box-Cox conversion combined with the Tukey method to normalize the data and eliminate outliers. Subgroups are divided according to gender and age to examine the division of RIs. The Z-test was used to compare differences between groups, and 95% distribution RIs were calculated using a nonparametric method.

RESULTS

In the study, we observed that the RIs for serum ferritin and Des-γ-carboxy prothrombin (DCP) were wider for men, ranging from 64.18 to 865.80 ng/ml and 14.00 to 33.00 mAU/ml, respectively, compared to women, whose ranges were 52.58 to 585.88 ng/ml and 13.00 to 29.00 mAU/ml. For other biomarkers, the overall RIs were established as follows: alpha-fetoprotein (AFP) 0-6.75 ng/ml, carcinoembryonic antigen (CEA) 0-4.85 ng/ml, carbohydrate antigen15-3 (CA15-3) for females 0-22.00 U/ml, carbohydrate antigen19-9 (CA19-9) 0-28.10 U/ml, carbohydrate antigen125 (CA125) 0-20.96 U/ml, cytokeratin 19 fragment (CYFRA21-1) 0-4.66 U/ml, neuron-specific enolase (NSE) 0-19.41 ng/ml, total and free prostate-specific antigens (tPSA and fPSA) for males 0-5.26 ng/ml and 0-1.09 ng/ml. The RIs for all these biomarkers have been validated through our rigorous processes.

CONCLUSION

This study preliminarily established 95% RIs for an apparently healthy elderly population in Southwestern China. Using real-world data and an indirect method, simple and reliable RIs for an elderly population can be both established and verified, which are suitable for application in various clinical laboratories.

Reference intervals of 14 biochemical markers for children and adolescence in China: the PRINCE study

OBJECTIVES

The Pediatric Reference Intervals in China (PRINCE) was initiated to establish the reference intervals (RIs) of Chinese children, as well as to make it possible to compare the variability of biochemical markers among countries internationally.

METHODS

Healthy participants, aged up to 20 years, from 11 provinces across China, were enrolled in PRINCE and according to a standard screening procedure, that included a questionnaire survey, physical examinations and laboratory tests. Fasting venous blood specimens were collected. All serum specimens were analyzed with Cobas C702 in the center laboratory, i.e. clinical laboratory of Beijing Children's Hospital, with certified qualification (ISO15189). The nonparametric method recommended by Clinical Laboratory Standards Institute guidelines, was used to calculate the age- and sex-specified RIs.

RESULTS

Among the 15,150 participants enrolled, 12,352 children (6,093 males and 6,259 females) were included to calculate RIs. The RIs for total protein, albumin, globulin, calcium, phosphate, potassium, sodium, chlorine, alkaline phosphatase, γ-glutamyl transpeptadase, alanine aminotransferase, aspartate aminotransferase, creatinine and urea were established by age- or sex-partitions. Most biochemical markers displayed larger variability and higher dispersion during the periods between 28 days and 1 year old, and included 4-6 age partitions commonly during 1 to <20 years old. In addition, differences of RIs between sexes usually occurs around the initiation of puberty at 12-13 years old.

CONCLUSIONS

The age- and sex-specified RIs of 14 biochemical markers in PRINCE study can provide a solid reference, which will be transferred into relevant RIs for other clinical laboratory's platforms according to the CLSI guidelines.

Age and sex specific reference intervals of 13 hematological analytes in Chinese children and adolescents aged from 28 days up to 20 years: the PRINCE study

OBJECTIVES

Pediatric Reference Intervals in China (PRINCE) is a nationwide initiative that aims to establish and validate harmonized reference intervals (RIs) for Chinese children and adolescents, in which 15,150 healthy volunteers aged up to 20 years were recruited from 11 centers to establish RIs and 7,557 children and adolescents were enrolled from 21 centers to validate RIs.

METHODS

The complete blood cell counts (CBC) of venous whole blood were measured by hematology analyzers through Sysmex systems in different centers. Age- and sex-specific RIs were calculated according to the guidelines.

RESULTS

Unlike adults with certain levels of analyte concentrations, hematological parameters of children changed through growth and development. Red blood cell counts, hemoglobin, and hematocrit increased with age, and revealed higher concentrations in boys than girls after puberty. White blood cell counts and platelet counts showed significant higher levels than adults before 2 years of age, and then gradually decreased without distinct sex differences. In addition, lymphocyte counts decreased with age while neutrophil counts showed an opposite trend. The lower and upper limits of pediatric RIs of CBC were different from those of adults.

CONCLUSIONS

The validation of RIs indicated that the PRINCE study provided a version of RIs suitable for most of regions in China. This first harmonized pediatric RIs of CBC across China provided a robust database to understand the dynamic changes of hematologic parameters from birth to adolescence, and will contribute to clinical diagnosis and prognosis evaluation for pediatric patients as well.

Comparison of reference distributions acquired by direct and indirect sampling techniques: exemplified with the Pediatric Reference Interval in China (PRINCE) study

BACKGROUND

Our study aimed to compare the reference distributions of serum creatinine and urea obtained by direct sampling technique and two indirect sampling techniques including the Gaussian Mixture Model (GMM) and the Self-Organizing Map (SOM) clustering based on clinical laboratory records, so that the feasibility as well as the potential limitations of indirect sampling techniques could be clarified.

METHODS

The direct sampling technique was used in the Pediatric Reference Interval in China (PRINCE) study, in which 15,150 healthy volunteers aged 0 to 19 years were recruited from 11 provinces across China from January 2017 to December 2018. The indirect sampling techniques were used in the Laboratory Information System (LIS) database of Beijing Children's Hospital, in which 164,710 outpatients were included for partitioning of potential healthy individuals by GMM or SOM from January to December 2016. The reference distributions of creatinine and urea that were established by the PRINCE study and the LIS database were compared.

RESULTS

The density curves of creatinine and urea based on the PRINCE data and the GMM and SOM partitioned LIS data showed a large overlap. However, deviations were found in reference intervals among the three populations.

CONCLUSIONS

Both GMM and SOM can identify potential healthy individuals from the LIS data. The performance of GMM is consistent and stable. However, GMM relies on Gaussian fitting, and thus is not suitable for skewed data. SOM is applicable for high-dimensional data, and is adaptable to data distribution. But it is susceptible to sample size and outlier detection strategy.

Continuous reference intervals for 21 biochemical and hematological analytes in healthy Chinese children and adolescents: the PRINCE study

OBJECTIVES

Critical gaps have existed in pediatric reference intervals in China. In this study, we presented the sex and age distributions of 21 laboratory analytes from childhood to adolescence, and established the corresponding continuous reference intervals based on direct samples.

METHODS

We used the data from the Pediatric Reference Intervals in China (PRINCE), which is a nation-wide cross-sectional study enrolling 15,150 healthy children and adolescents aged 0 - <20 years from 11 centers across China. Blood samples were collected and analyzed by trained staff following standard operating procedures. Biochemical tests were performed with Cobas C702 at the central laboratory, and hematological tests were performed with Sysmex XE, XN, or XS that satisfy the national standards at each participating center. Children younger than 3 months were excluded due to high neonatal variability and insufficient samples. Continuous reference intervals were calculated using the generalized additive models for location, shape, and scale, and were validated among another 387 healthy volunteers.

RESULTS

We provided pediatric continuous reference intervals for 21 commonly used biochemical and hematological analytes in China, and depicted the changes in analyte concentrations from 3 months to 20 years. The out-of-range values for all analytes were less than 10%, indicating a well applicability of the continuous reference intervals to the general pediatric population.

CONCLUSIONS

This is the first comprehensive report of continuous reference intervals based on healthy Chinese children, reflecting the complex dynamic trends of analytes from infancy to adulthood. Applying continuous reference intervals to clinical practice would not only improve the laboratory test result interpretation, but also help better clinical decision making.

Big data and reference intervals: rationale, current practices, harmonization and standardization prerequisites and future perspectives of indirect determination of reference intervals using routine data

Reference intervals are commonly used as a decision-making tool. In this review, we provide an overview on "big data" and reference intervals, describing the rationale, current practices including statistical methods, essential prerequisites concerning data quality, including harmonization and standardization, and future perspectives of the indirect determination of reference intervals using routine laboratory data.

Establishment of age- and sex-specific reference intervals for serum liver function tests in pediatric population aged 1-<18 years: A prospective study

Background

The diagnosis, treatment, and prognosis of pediatric diseases rely on the accurate establishment of the reference interval (RI). This study aimed to establish pediatric RIs for liver function tests and evaluated the correlation of the analytes.

Methods

Pediatric population (aged 1–<18 years) was prospectively recruited in Jilin Province, China. Analytes detected by Ortho VITORS 5600 automatic biochemical analyzer. All strata were divided using the regression tree and Harris and Boyd's method. The dynamic changes of RI were evaluated by the lambda‐mu‐sigma method.

Results

Reference individuals were comprised of 6,322 children and adolescents. Age and sex differences were present in all analytes except serum total protein. The serum albumin, total protein, γ‐glutamyl transferase, total bilirubin, and unconjugated bilirubin levels increased with age while serum aspartate aminotransferase was opposite. The serum alanine aminotransferase level reached a trough at the age of 5 and later steadily in males but slowly decreased in females. The serum alkaline phosphatase level dropped rapidly after reaching a peak at 9 years old in females and 12 years old in males. RIs were divided into 11 partitions at most and 5 partitions at least. The strongest correlation between analytes was total bilirubin and unconjugated bilirubin (r = 0.788), followed by total bilirubin and albumin (r = 0.511).

Conclusions

Analytes show unique dynamic changes in pediatric population. The correlations among liver function tests can inform future studies of particular variables. Age‐ and sex‐special pediatric RIs should be established to help an accurate diagnosis of disease.

Age-dependent changes of total and differential white blood cell counts in children

BACKGROUND

Total and differential white blood cell counts are important for the diagnostic evaluation of suspected diseases. To facilitate the interpretation of total and differential white blood cell counts in pediatric patients, the present study investigated age-dependent changes in total and differential white blood cell counts in healthy reference children.

METHODS

Data were obtained from the Pediatric Reference Intervals in China study (PRINCE), which aims to establish and verify pediatric reference intervals for Chinese children based on a nationwide multicenter cross-sectional study from January 2017 to December 2018. Quantile curves were calculated using the generalized additive models for location, shape, and scale method. The 2.5th, 50th, and 97.5th quantile curves were calculated for both total and differential white blood counts. Percents of stacked area charts were used to demonstrate the proportions of differential white blood cells. All statistical analyses were performed using R software.

RESULTS

Both 50th and 97.5th quantiles of total white blood cell count and monocyte count were highest at birth, then rapidly decreased in the first 6 months of life; relatively slow reduction continued until 2 years of age. The lymphocyte count was low during infancy and increased to its highest level at 6 months of age; it then exhibited moderate and continuous reduction until approximately 9 years of age. The pattern of neutrophil count changed with age in a manner opposite to that of lymphocyte count. Besides, there were two inter-sections of lymphocyte count and neutrophil count during infancy and at approximately 5 years of age, based on locally weighted regression (LOESS) analysis. There were no apparent age-related changes in eosinophil or basophil counts.

CONCLUSION

These data regarding age-related changes in total and differential white blood cell counts can be used to assess the health of pediatric patients and guide clinical decisions.

Comparison of four algorithms on establishing continuous reference intervals for pediatric analytes with age-dependent trend

BACKGROUND

Continuous reference intervals (RIs) allow for more precise consideration of the dynamic changes of physiological development, which can provide new strategies for the presentation of laboratory test results. Our study aimed to establish continuous RIs using four different simulation methods so that the applicability of different methods could be further understood.

METHODS

The data of alkaline phosphatase (ALP) and serum creatinine (Cr) were obtained from the Pediatric Reference Interval in China study (PRINCE), in which healthy children aged 0-19 years were recruited. The improved non-parametric method, the radial smoothing method, the General Additive Model for Location Scale and Shape (GAMLSS), and Lambda-Median-Sigma (LMS) were used to develop continuous RIs. The accuracy and goodness of fit of the continuous RIs were evaluated based on the out of range (OOR) and Akaike Information Criterion (AIC) results.

RESULTS

Samples from 11,517 and 11,544 participants were used to estimate the continuous RIs of ALP and Cr, respectively. Time frames were partitioned to fulfill the following two criteria: sample size = 120 in each subgroup and mean difference = 2 between adjacent time frames. Cubic spline or penalized spline was used for curve smoothing. The RIs estimated by the four methods approximately overlapped. However, more obvious edge effects were shown in the curves fit by the non-parametric methods than the semi-parametric method, which may be attributed to insufficient sample size. The OOR values of all four methods were smaller than 10%.

CONCLUSIONS

All four methods could be used to establish continuous RIs. GAMLSS and LMS are more reliable than the other two methods for dealing with edge effects.

Reference intervals for gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system

The aim of this study is to establish the reference intervals (RIs) for serum gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system. According to CLSI EP28-A3, the appropriate statistical analysis method was selected and the RIs were determined using the indirect method based on the analysis results. All the test data of the four research projects showed a skewness distribution (p < .05). Gender and age are two important factors influencing the level of detection value. According to the analysis results, the data of the four research projects were grouped by gender and age, and the non-parametric percentile method (95%, double-sided) was used to establish the RIs of each group. The established RIs were validated using the method of Reference Change Value (RCV). The relative deviations between the upper limit value of reference interval in each group of AFP and CEA and that provided by the manufacturer is all smaller than the RCV of eath, so the RIs established by this study is proved to be reliable. While, the relative deviation of the group CEA (male > 40 years old, female > 60 years old) and CA724 is higher than each RCV, which indicates that the RIs provided by the manufacturer is not applicable to the test population and test system of the laboratory. We established RIs of serum gastrointestinal tumor markers (AFP, CEA, CA199 and CA724) in healthy adults of Han nationality in Chongqing by Roche ECLIA system. Furthermore, our study suggests that it is necessary to establish the age-specific and sex-specific RIs for gastrointestinal tumor markers in different detection systems.

Pediatric reference intervals in China (PRINCE): design and rationale for a large, multicenter collaborative cross-sectional study

There is a lack of accurate pediatric reference intervals (RIs) in China, with most commonly used RIs established without consideration of the effect of age and gender. The Pediatric Reference Intervals in China (PRINCE) project aims to establish and verify pediatric RIs for 31 common laboratory measurands. The project will be a large, multicenter cross-sectional study: 14,490 healthy children and adolescents aged up to 19 years will be surveyed by 10 children's hospitals and one pediatric department of a university hospital. To evaluate the feasibility and efficiency of the study methods, 602 children were surveyed in the pilot phase of the PRINCE study in April 2017: it found that some measurands were distinctly age dependent and that there were differences between values for males and females. The results of the pilot study affirmed the necessity of the PRINCE project for Chinese pediatrics. The pilot also indicated potential difficulties in the full survey, e.g., difficulties in recruiting children aged under 3 years and insufficient collection of blood samples from infants. The operation of the PRINCE project has been modified based on the findings in the pilot study toward improving the validity of the PRINCE project and promoting its openness and transparency.