Ahmet Mete Çilingirtürk

Verifying reference intervals for coagulation tests by using stored data

Abstract Objective: The purpose of the study was to verify the reference intervals for prothrombin time (PT) and activated partial thromboplastin time (APTT), using stored data of ambulatory pre-op subjects with exclusion of certain clinics, according to age and sex. Materials and Methods: Results of test requests (13,600 PT and 14,083 APTT) of subjects aged 15–80 made from outpatient clinics of surgical departments before surgical interventions in 2008 were retrieved from the electronic medical record. Thromborel S and Actin (Dade Behring, Germany) were used on the Sysmex® CA-1500 coagulation analyzer. Extreme values were determined by using Horns algorithm after Box-Cox transformation, and the upper and lower reference limits were determined as the 2.5th and 97.5th percentiles of the cleaned data. Results: The values outside the interval of PT data 10.5–17.0 seconds and the interval of APTT data 20.6–35.8 seconds were excluded from the analysis. There were significant differences among age subsets of PT measurements ( p < 0.0001) and of APTT measurements ( p < 0.0001). Accordingly, the data were tested for gender differences and a significant difference was found in PT ( p = 0.002). APPT results did not differ statistically between men and women. Conclusion: Although we found values different from the limits stated in the kit insert, it would be better to confirm our findings with the direct method, especially in APTT for patients under the age of 40 and over the age of 59, and also for sex differences in PT.

Pediatric reference intervals of free thyroxine and thyroid stimulating hormone in three different hospitals

Abstract Objective: Using data retrieved from three different hospitals, we established indirect reference intervals of free thyroxine (FT4) and thyroid stimulating hormone (TSH) for the Centaur XP or the Immulite 2000 instruments, in separate reference limits at each subset. Methods: We categorized children into seven age groups: 4–7 days, 8–15 days, 16–23 days, 24–61 days, 3–6 months, 7–36 months and 4–6 years. After a Box-Cox transformation was employed, we followed the Horn algorithm to eliminate the extreme values. Results: The remaining FT4 (11,230) and TSH (11,274) tests were statistically analyzed. We determined separate reference limits at each subset with their own 2.5th and 97.5th percentiles. The interaction effect of both hospital and age grouping on FT4 was meaningful, but there was no interaction effect on TSH. Conclusions: Pediatric FT4 and TSH test results should be interpreted via narrowed age groups, especially in the first 3 weeks of neonatal period. Our reference limits may be recommended in pediatric follow-ups, considering the conditions of prematurity, birth-weight or multiple births. Preanalytical and analytical variations related with complex molecular structure of FT4 should be taken into consideration to ensure the validity of the result.

Does Institutional Rank Ordering Qualitative or Quantitative

In competitive markets, companies search their positions according to their competitors with internal resources or make use of the services of market research firms. Various credit and rating agencies or co-ordination for sectors with some social and political remediation also examine and rank the companies in these sectors. These companies are listed on the Stock Exchange Istanbul. Petroleum and derivatives industries, which are important sources of energy for industrial and Turkey, have been reconsidered in the Fortune 500 ranking by MOORA and COPRAS optimization methods and with statistical factor analysis with various efficiency and size indicating financial ratios. The results obtained are consistent within themselves and differ from the Fortune 500 rank order. The difference between quality and quantity can lead companies to wrong strategies in this sort of ranking. The study might be important to bring out efficiency and productivity in the sense of planning possible strategic changes.

Assessment of average of normals (AON) procedure for outlier-free datasets including qualitative values below limit of detection (LoD): an application within tumor markers such as CA 15-3, CA 125, and CA 19-9

Abstract Average of normals (AON) is a quality control procedure that is sensitive only to systematic errors that can occur in an analytical process in which patient test results are used. The aim of this study was to develop an alternative model in order to apply the AON quality control procedure to datasets that include qualitative values below limit of detection (LoD). The reported patient test results for tumor markers, such as CA 15-3, CA 125, and CA 19-9, analyzed by two instruments, were retrieved from the information system over a period of 5 months, using the calibrator and control materials with the same lot numbers. The median as a measure of central tendency and the median absolute deviation (MAD) as a measure of dispersion were used for the complementary model of AON quality control procedure. The ubias values, which were determined for the bias component of the measurement uncertainty, were partially linked to the percentages of the daily median values of the test results that fall within the control limits. The results for these tumor markers, in which lower limits of reference intervals are not medically important for clinical diagnosis and management, showed that the AON quality control procedure, using the MAD around the median, can be applied for datasets including qualitative values below LoD.