A Progress Report of the IFCC Committee for Standardization of Thyroid Function Tests.

BACKGROUND: The IFCC Committee for Standardization of Thyroid Function Tests aims at equivalence of laboratory test results for free thyroxine (FT4) and thyrotropin (TSH). OBJECTIVES: This report describes the phase III method comparison study with clinical samples representing a broad spectrum of thyroid disease. The objective was to expand the feasibility work and explore the impact of standardization/harmonization in the clinically relevant concentration range. METHODS: Two sets of serum samples (74 for FT4, 94 for TSH) were obtained in a clinical setting. Eight manufacturers participated in the study (with 13 FT4 and 14 TSH assays). Targets for FT4 were set by the international conventional reference measurement procedure of the IFCC; those for TSH were based on the all-procedure trimmed mean. The manufacturers recalibrated their assays against these targets. RESULTS: All FT4 assays were negatively biased in the mid- to high concentration range, with a maximum interassay discrepancy of approximately 30%. However, in the low range, the maximum deviation was approximately 90%. For TSH, interassay comparability was reasonable in the mid-concentration range, but worse in the pathophysiological ranges. Recalibration was able to eliminate the interassay differences, so that the remaining dispersion of the data was nearly entirely due to within-assay random error components. The impact of recalibration on the numerical results was particularly high for FT4. CONCLUSIONS: Standardization and harmonization of FT4 and TSH measurements is feasible from a technical point of view. Because of the impact on the numerical values, the implementation needs careful preparation with the stakeholders.

Anti-CCP: challenges in quantifying auto-antibodies and creating international reference materials.

Anti-CCP assays (antibody to cyclic citrullinated peptides) possess a high specificity for RA (rheumatoid arthritis). In lack of an international reference material the absolute values among different assays strongly diversify. The cut-off showed a variance from 5 U/mL Euroimmun anti-CCP to 25 U/mL Euro-Diagnostica Immunosan RA. The Autoantibody Standardization Committee is currently trying to establish a reference specimen of human polyclonal anti-CCP.

Proposal of a candidate international conventional reference measurement procedure for free thyroxine in serum.

In the present paper the IFCC WG-STFT recommends and provides the rationale to establish metrological traceability of serum free thyroxine (FT4) measurements to a candidate international conventional reference measurement procedure. It is proposed that this procedure be based on equilibrium dialysis combined with determination of thyroxine in the dialysate with a trueness-based reference measurement procedure. The measurand is thus operationally defined as "thyroxine in the dialysate from equilibrium dialysis of serum prepared under defined conditions". With regard to the trueness-based reference measurement procedure, the WG-STFT recommends use of an isotope dilution-liquid chromatography/tandem mass spectrometry (ID-LC/tandem MS) procedure for total thyroxine that has been optimized towards measurement at picomolar concentration levels and that is listed in the database of the Joint Committee for Traceability in Laboratory Medicine (JCTLM). For calibration, the purified thyroxine material IRMM-468 (resulting from a project funded by the European Commission and recently submitted to the JCTLM) is proposed. The WG-STFT stresses that according to this recommendation it is a prerequisite to strictly adhere to the defined equilibrium dialysis procedure, whereas it is permissible to introduce variants in the ID-LC/tandem MS procedure.

Methodological quality of patient-reported outcome research was low in complementary and alternative medicine in oncology.

OBJECTIVE: To evaluate the methodological robustness of patient-reported outcomes (PROs) evaluation in complementary and alternative medicine (CAM) randomized controlled trials (RCTs) in oncology. STUDY DESIGN AND SETTING: CAM RCTs with a PRO endpoint were retrieved from a number of electronic databases. CAM interventions were defined according to the five major categories of the National Center for Complementary and Alternative Medicine. The "Minimum Standard Checklist for Evaluating HRQOL Outcomes in Cancer Clinical Trials" was used to assess the quality of the PRO reporting in these trials. RESULTS: Forty-four RCTs enrolling 4,912 patients were identified: six studies involved alternative medical systems, 14 involved mind body interventions, 15 dealt with biologically-based therapies, seven involved manipulative and body-based methods, and two energy therapies. Eighty-nine percent of studies used a PRO as a primary endpoint and 59% documented PRO missing data. Although 84% of the studies used a validated PRO questionnaire, only 37% stated an a priori hypothesis and 20% addressed clinical significance of the outcomes. Overall, 64% of the studies analyzed exhibited a number of methodological drawbacks. CONCLUSIONS: To facilitate the interpretation of results from such CAM RCTs, investigators are encouraged to pay greater attention to key methodological issues as identified in this study.