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PubMed2002

[Systematic reviews in practice. X. Searching, selecting and the methodological assessment of diagnostic evaluation research].

Literature concerning the value of diagnostic tests is poorly indexed in electronic bibliographical databases. An extensive, sensitive and specific search strategy for evaluation of a diagnostic test in Medline is a combination of key words or text words concerning the diagnostic test with: 'sensitivity and specificity' (exploded), 'mass screening' (exploded), 'reference values', 'false positive reactions', 'false negative reactions', 'specificit$.tw', 'screening.tw', 'false positive$.tw', 'false negative$.tw', 'accuracy.tw', 'predictive value$.tw', 'reference value$.tw', 'roc$.tw' or 'likelihood ratio$.tw'. Inclusion and exclusion criteria select publications which meet certain minimum requirements, such as the presence of an accepted reference standard, a clear definition of 'diseased', and the presence of a suitable outcome measure. The methodological assessment list should contain a number of validity criteria as well as a number of criteria by which to measure the extent to which the study results can be generalised. Important assessment criteria that may affect the diagnostic value of the test are: study design, blinding, use of different reference standards, the absence of details about the diagnostic criteria for the diagnostic test and insufficient information about the study population.

Diagnostic Tests, Routine↗
PubMed2006

Accuracy of radiographers red dot or triage of accident and emergency radiographs in clinical practice: a systematic review.

AIM: To determine the accuracy of radiographers red dot or triage of accident and emergency (A&E) radiographs in clinical practice. MATERIALS AND METHODS: Eligible studies assessed radiographers red dot or triage of A&E radiographs in clinical practice compared with a reference standard and provided accuracy data to construct 2 x 2 tables. Data were extracted on study eligibility and characteristics, quality, and accuracy. Pooled sensitivities and specificities and chi-square tests of heterogeneity were calculated. RESULT: Three red dot and five triage studies were eligible for inclusion. Radiographers' red dot of A&E radiographs in clinical practice compared with a reference standard is 0.87 [95% confidence interval (CI) 0.85-0.89] and 0.92 (0.91-0.93) sensitivity and specificity, respectively. Radiographers' triage of A&E radiographs of the skeleton is 0.90 (0.89-0.92) and 0.94 (0.93-0.94) sensitivity and specificity, respectively; and for chest and abdomen is 0.78 (0.74-0.82) and 0.91 (0.88-0.93). Radiographers' red dot of skeletal A&E radiographs without training is 0.71 (0.62-0.79) and 0.96 (0.93-0.97) sensitivity and specificity, respectively; and with training is 0.81 (0.72-0.87) and 0.95 (0.93-0.97). Pooled sensitivity and specificity for radiographers without training for the triage of skeletal A&E radiographs is 0.89 (0.88-0.91) and 0.93 (0.92-0.94); and with training is 0.91 (0.88-0.94) and 0.95 (0.93-0.96). CONCLUSION: Radiographers red dot or triage of A&E radiographs in clinical practice is affected by body area, but not by training.

Clinical Competence↗
PubMedDate not supplied

Application of accurate mass measurement to urine drug screening.

Poor availability of reference standards for designer drugs, metabolites, and new substances prevents toxicology laboratories from rapidly responding to the changing analytical challenges of drug abuse. A novel screening approach comprising determination of accurate masses of sample components and comparison of these with databases of theoretical monoisotopic masses is described. Using liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS), a routine mass search window of 20-30 ppm was applied to urine samples. The ultimate reference technique, liquid chromatography-Fourier transform mass spectrometry (LC-FTMS), was capable of confirming the findings within a 3 ppm mass accuracy. Using a target database of 7640 compounds, the number of potential elemental formulas ranged from one to three with LC-TOFMS, and it was always one with LC-FTMS. In contrast to ordinary techniques requiring primary reference standards, the formula-based databases can be updated instantly with fresh numeric data from scientific literature and authority sources.

Chromatography, High Pressure Liquid↗
PubMed2005

Diagnostic accuracy of chest radiography in detecting mediastinal lymphadenopathy in suspected pulmonary tuberculosis.

OBJECTIVE: To estimate the diagnostic accuracy of chest radiography in the detection of chest lymphadenopathy in children with clinically suspected pulmonary tuberculosis. METHODS DESIGN: Prospective cross sectional study. SETTING: A short stay ward in a children's hospital in South Africa. PATIENTS: Consecutive children under 14 years of age admitted with suspected pulmonary tuberculosis. DIAGNOSTIC TEST: Antero-posterior and/or lateral chest x rays interpreted independently and blind to the reference standard by three primary care clinicians and three paediatricians, all with a special interest in tuberculosis. Reference standard: Spiral chest computed tomography (CT) with contrast injection. RESULTS: One hundred children (median age 21.5 months) were enrolled. Lymphadenopathy was present in 46 of 100 reference CT scans and judged to be present in 47.1% of x ray assessments. Overall sensitivity was 67% and specificity 59%. Primary care clinicians were more sensitive (71.5% v 63.3%, p = 0.047) and less specific (49.8% v 68.9%, p<0.001) than paediatricians. Overall accuracy was higher for the paediatricians (diagnostic odds ratio 3.83 v 2.49, p = 0.008). The addition of a lateral to an antero-posterior view did not significantly increase accuracy (diagnostic odds ratio 3.09 v 3.73, p = 0.16). Chance adjusted inter-observer agreement (kappa) varied widely between viewer pairs, but was around 30%. CONCLUSIONS: Detection of mediastinal lymphadenopathy on chest x ray to diagnose pulmonary tuberculosis in children must be interpreted with caution. Diagnostic accuracy might be improved by refining radiological criteria for lymphadenopathy.

Child, Preschool↗
PubMed2005

Nutritional and technological behavior of stabilized iron-gluconate in wheat flour.

Food fortification has been shown to be an effective strategy to overcome iron malnutrition. When a new iron compound is developed for this purpose, it must be evaluated from a nutritional and technological point of view before adding it into foods. In this way, we have evaluated ferrous gluconate stabilized by glycine as a new iron source to be used in wheat flour fortification. We performed biological studies in rats as well as sensory perceptions by human subjects in wheat flour fortified with this iron source. The productions of pentane as a rancidity indicator as well as the change of the sensorial properties of the biscuits made with stabilized ferrous gluconate-fortified wheat flour were negligible. Iron absorption in water from this iron source was similar to the reference standard ferrous sulfate. Nevertheless, because of the phytic acid content, iron absorption from fortified wheat flour decrease 40% for both iron sources. The addition of zinc from different sources did not modify iron absorption from ferrous sulfate and stabilized ferrous gluconate in water and wheat flour. The iron absorption mechanism as well as the biodistribution studies demonstrate that the biological behavior of this iron source does not differ significantly from the reference standard. These results demonstrate that the iron source under study has adequate properties to be used in wheat flour fortification. Nevertheless, more research is needed before considering this iron source for its massive use in food fortification.

Animals↗
PubMed2004

Comparison of three commercially available thrombomodulin ELISA kits.

Thrombomodulin is a transmembranous glycoprotein of endothelial cells. In vitro it is a marker of endothelial cell injury. In vivo the levels of soluble serum thrombomodulin are regarded as parameters of disease activity in vasculitides and vasculopathies. However, the mean thrombomodulin values of different studies show marked concentration differences of the control values. The purpose of this study was to further investigate these differences. We examined 60 sera of patients with systemic lupus erythematosus (SLE) and 10 of healthy controls with three commercially available thrombomodulin ELISA kits for determination of their thrombomodulin concentration and correlation to disease activity. The disease activity of the SLE patients was determined with the SLAM-score. Raised thrombomodulin values were found in 58% (test A), 55% (test B) and 61.6% (test C). The thrombomodulin values significantly correlated with the SLE disease activity independently of the ELISA kit used (correlation coefficients: r=0.84 (test A), r=0.80 (test B), and r=0.65 (test C)). In addition, the correlation coefficients between the respective thrombomodulin values of the three tests were r=0.86 (test A to B), r=0.73 (test A to C) and r=0.79 (test B to C). However, significant differences between the results of the three ELISA kits were found between the detected thrombomodulin concentrations. The mean thrombomodulin concentrations of the controls were 25.6 ng/ml (test A), 3.53 ng/ml (test B), and 2.52 ng/ml (test C). Our results reveal that the soluble thrombomodulin values of all three commercially available ELISA kits significantly correlate with the disease activity of SLE patients. However, the results show significant differences in the determined thrombomodulin concentrations. A calibration would be required of the different ELISA kits in order to permit a direct comparison of the results of these thrombomodulin ELISAs. A general reference standard would be desirable for this calibration of all thrombomodulin ELISAs. However, this general reference standard has to be adapted to the distinct test conditions of all test kits as well as including all epitopes of thrombomodulin which are recognised by the different antibodies used in the respective test kits. At present, only ELISA kits from the same manufacturer should be used during a single study including any follow-up investigations.

Adolescent↗
PubMed2005

Comparison of the validity and reliability of two image classification systems for the assessment of mammogram quality.

OBJECTIVE: To compare the reliability and validity of two classification systems used to evaluate the quality of mammograms: PGMI ('perfect', 'good', 'moderate' and 'inadequate') and EAR ('excellent', 'acceptable' and 'repeat'). SETTING: New South Wales (Australia) population-based mammography screening programme (BreastScreen NSW). METHODS: Thirty sets of mammograms were rated by 21 radiographers and an expert panel. PGMI and EAR criteria were used to assign ratings to the medio-lateral oblique (MLO) and cranio-caudal (CC) views for each set of films. Inter-observer reliability and criterion validity (compared with expert panel ratings) were assessed using mean weighted observed agreement and kappa statistics. RESULTS: Reliability: Kappa values for both classification systems were low (0.01-0.17). PGMI produced significantly higher values than EAR. Agreement between raters was higher using PGMI than EAR for the MLO view (77% versus 74%, P < 0.05), but was similar for the CC view. Dichotomized ratings ('acceptable' or 'needs repeating') did not improve reliability estimates. VALIDITY: Kappa values between raters and the reference standard were low for both classification systems (0.05-0.15). Agreement between raters and the reference standard was higher using PGMI than EAR for the MLO view (74% versus 63%), but was similar for the CC view. Dichotomized ratings of the MLO view showed slightly higher observer agreement. CONCLUSIONS: Both PGMI and EAR have poor reliability and validity in evaluating mammogram quality. EAR is not a suitable alternative to PGMI, which must be improved if it is to be useful.

Breast Neoplasms↗
PubMed2004

Nutrition screening and assessment of anthropometry and bioelectrical impedance in the frail elderly: a clinical appraisal of methodology in a clinical setting.

Nutrition screening is recommended to identify those at risk for malnutrition; nutrition assessment by anthropometry and impedance is widely used to indicate nutritional status but may be problematical in the frail elderly in nursing homes. Acceptability, availability, suitability and appropriate reference data influence clinical application of these measurements. In our study, nutrition screening and assessment methodology were evaluated in 46 nursing home residents, mean age 86.3 +/- 6.6 years, mean weight 66.1 +/- 12.9 kg, mean height 163.1 +/- 9.6 cm, and mean BMI 24.9 +/- 4.6 kg/m2. Significant correlations (P < 0.05) were found in all measures of body weight, BMI, body fatness and leanness. Interpretation of data by five different reference standards and cutoff points revealed wide variation in identification of malnutrition by anthropometry. Appropriate reference data for body lean and fatness are not yet available. Thus, population-specific methodology and reference standards are of crucial importance.

Aged↗
PubMedDate not supplied

Chronobiology of human blood pressure in the light of static (room-restricted) automatic monitoring.

Systematic 24-h automatic physiologic monitoring has obvious merits, even without rhythmometry. It can lead more readily to the recognition of odd-hour blood pressure elevation (e.g., of 'evening' or 'morning' hypertension). Such a condition can constitute an initial diagnosis or it may be found under treatment that may seem to be satisfactory if its effects are assessed only on the basis of a conventional check at a casual, possibly 'wrong' time. The mere inspection of a 24-h record, however, does not necessarily allow one to make objective quantitative global statements as to a change in pattern, e.g., after a given intervention. This paper illustrates how by rhythmometry, some of the uncertainties of a subjective interpretation of a record may be removed by practitioners of medicine, as well as basic scientists interested in mechanisms of blood pressure variability. This is possible since a large part of blood pressure variability can be accounted for by its circadian periodic behavior. We herein present a methodology for data collection and analysis that allows the objective quantification of blood pressure rhythm parameters in health and disease and the derivation of reference standards for such parameters. The chronobiologic approach thus makes it possible to define 'hypertension' objectively, and to distinguish between 'mesor-' and 'amplitude-hypertension', i.e., between an elevation in overall mean and one in the predictable extent of variability. Moreover, chronobiology has shown that mesor-hypertension may be preceded by an elevation in circadian amplitude only (amplitude-hypertension). Parameter tests readily allow the assessment, in relation to an objective reference standard, of these conditions, with a defined probability. Similarly, response to drug or non-drug therapy can be established and a given intervention optimized by timing treatment. Using chronobiologic tools in cardiovascular research provides new insights into possible mechanisms underlying mesor- and amplitude-hypertension. The teaching of the chronobiology of blood pressure and autorhythmometry in schools has been proven to be feasible and has been recommended as a step toward self-help for health care.

Adolescent↗
PubMedDate not supplied

Determination of isoflavones in soy and selected foods containing soy by extraction, saponification, and liquid chromatography: collaborative study.

Isoflavones are biologically active compounds occurring naturally in a variety of plants, with relatively high levels found in soybeans. Twelve laboratories participated in a collaborative study to determine the aglycon isoflavone content of 8 test samples of soy and foods containing soy. The analytical method for the determination of isoflavones incorporates a mild saponification step that reduces the number of analytes measured and permits quantitation versus commercially available, stable reference standards. Test samples were extracted at 65 degrees C with methanol-water (80 + 20), saponified with dilute sodium hydroxide solution, and analyzed by reversed-phase liquid chromatography with UV detection at 260 nm. Isoflavone results were reported as microg/aglycon/g or microg aglycon equivalents/g. The 8 test samples included 2 blind duplicates and 4 single test samples with total isoflavone concentrations ranging from approximately 50 to 3000 microg/g. Test samples of soy ingredients and products made with soy were distributed to collaborators with appropriate reference standards. Collaborators were asked to analyze test samples in duplicate on 2 separate days. The data were analyzed for individual isoflavone components, subtotals of daidzin-daidzein, glycitin-glycitein, and genistin-genistein, and total isoflavones. The relative standard deviation (RSD) for repeatability was 1.8-7.1%, and the RSD for reproducibility was 3.2-16.1% for total isoflavone values of 47-3099 microg/g.

Chromatography, Liquid↗
PubMed2004

The potential contribution of a computer-aided detection system for lung nodule detection in multidetector row computed tomography.

RATIONALE AND OBJECTIVES: We sought to evaluate the potential benefits of a computer-aided detection (CAD) system for detecting lung nodules in multidetector row CT (MDCT) scans. METHODS: A CAD system was developed for detecting lung nodules on MDCT scans and was applied to the data obtained from 15 patients. Two chest radiologists in consensus established the reference standard. The nodules were categorized according to their size and their relationship to the surrounding structures (nodule type). The differences in the sensitivities between an experienced chest radiologist and a CAD system without user interaction were evaluated using a chi2 analysis. The differences in the sensitivities also were compared in terms of the nodule size and the nodule type. RESULTS: A total of 309 nodules were identified as the reference standard. The sensitivity of a CAD system (81%) was not significantly different from that of a radiologist (85%; P > 0.05). The sensitivities of the CAD system for detecting nodules < or = 5 mm in diameter as well as detecting isolated nodules were higher than those of a radiologist (83% vs. 75%, P > 0.05; 93% vs. 76%, P < 0.001). The sensitivities of a radiologist for detecting nodules >5 mm and the nodules attached to other structures were higher than those of a CAD system (98% vs. 79%, P < 0.001; 91% vs. 71%, P < 0.001). There were 28.8 false-positive results of CAD per CT study. CONCLUSION: The CAD system developed in this study performed the nodule detection task in different ways to that of a radiologist in terms of the nodule size and the nodule type, which suggests that the CAD system can play a complementary role to a radiologist in detecting nodules from large CT data sets.

Adult↗
PubMed2000

Magnetic resonance evaluation of recurrent disc herniation: is gadolinium necessary?

STUDY DESIGN: Evaluation of magnetic resonance images (MRIs) with surgical reference standard. OBJECTIVES: To determine whether the addition of contrast-enhanced MRI scans increases diagnostic efficacy in the evaluation of recurrent disc herniation. SUMMARY OF BACKGROUND DATA: Many centers now routinely use gadolinium-enhanced examinations in the evaluation of recurrent disc herniation. Others, noting the additional expense of contrast injection, advocate a more limited role for contrast injection and emphasize the importance of T2-weighted axial sequences. METHODS: The study included 165 consecutive patients who were referred to the authors' outpatient imaging center and had a history of previous lumbar discectomy and recurrent back and/or leg pain. The scanning protocol included sagittal and axial T1-weighted spin-echo pre- and postcontrast injection images and sagittal and axial T2-weighted fast spin-echo images. Twenty-eight patients (32 vertebral levels) had subsequent surgical exploration of a disc margin that had previously undergone discectomy. The surgical findings formed the reference standard. Three spine radiologists interpreted the MRI examinations without knowledge of the surgical results. They first interpreted the unenhanced studies, indicated whether they felt contrast injection would be helpful in further evaluation, and then (regardless of this determination) read the postcontrast study. RESULTS: On pre- and post-contrast examinations Reader 1 had a sensitivity of 95% (20/21), a specificity of 100% (10/10), and an accuracy of 97% (30/31). Reader 2 had a sensitivity of 95% (20/21), a specificity of 90% (9/10), and an accuracy of 94% (29/31). Reader 3 had a sensitivity of 90% (19/21), a specificity of 100% (10/10), and an accuracy of 94% on the precontrast examinations. His postcontrast performance demonstrated a sensitivity of 86% (18/21), a specificity of 100% (10/10), and an accuracy of 90% (28/31). In the nine interpretations wherein the readers thought that a contrast-enhanced examination might provide useful additional information, they did not change their interpretations in three cases, improved their interpretations in two, and made their interpretations worse in four on the basis of addition of the enhanced images. CONCLUSIONS: Routine use of contrast-enhanced examinations in patients who have had prior lumbar surgery probably adds little diagnostic value and may be confusing.

Back Pain↗
PubMed2006

Adjustment of meta-analyses on the basis of quality scores should be abandoned.

OBJECTIVE: To find if a particular quality score was better than others at validly scoring the quality of randomized controlled trials, both by examining the consistency of dividing studies into high and low quality and using a large study as a reference standard. STUDY DESIGN AND SETTING: Observational study of meta-analyses from the Cochrane Library. These had to have binary outcomes that included more than 10 studies, one or more of which randomized more than 500 people into each group. RESULTS: Eighteen systematic reviews, with 65 meta-analyses using binary outcomes, were included and the included trials were scored for 43 different quality scores. None of these scores was better at dividing the studies in to low and high quality, and none of the scores was better over the 65 meta-analyses in making the result closer to the reference standard. CONCLUSION: None of the quality scores found appeared to measure quality validly. It is a mistake to assign meaning to the result of a quality score.

Bias↗
PubMedDate not supplied

Modified liquid chromatographic method for determination of gentian violet in animal feed.

A modified liquid chromatographic method is described for the determination of Gentian Violet (GV) in animal feed. The reliable detection limit is 0.5 ng (reference standards), and 1 ppm GV was reliably determined in feed. The calibration curve was linear between 1 and 40 micrograms/mL. The method, developed in a study by the National Center for Toxicological Research, was modified to use methanol-water (9 + 1) instead of benzene-methanol as the eluting solution in the column cleanup. GV is extracted from feed with methanol-1N HCl (99 + 1), cleaned up on a Sephadex LH-20 column to remove any remaining interferences, separated on a Nova-Pak C18 column fitted with a precolumn filter, and determined at 588 nm. The identity of GV is confirmed by thin-layer chromatography (Rf = 0.47) by comparison with a reference standard. Average recoveries from 3 sets of 5 feed samples containing 2.5, 5.0, and 10.0 ppm GV were 115, 95, and 102%, respectively.

Animal Feed↗
PubMed2004

Correlation of computed tomographic images with anatomic features of the abdomen of ringed seals (Phoca hispida).

OBJECTIVE: To correlate anatomic features of the abdomen of the ringed seal (Phoca hispida) identified in plastinated cross-sections with images obtained via computed tomography (CT) and thereby establish reference standards for normal abdominal organ size and position in this species. SAMPLE POPULATION: 2 adult male ringed seal cadavers. PROCEDURE: With the seal in sternal recumbency, CT images of the abdomen were acquired by use of a 4th-generation CT scanner. Image slice thickness was 1 cm, with no interslice gap. After imaging, the abdominal region was sectioned transversely into 4-cm slices, which were plastinated and photographed. Plastinated slices were matched to their corresponding CT images in preparation for anatomic descriptions. RESULTS: Relevant anatomic features were identified and labeled on both the plastinated tissue slice and corresponding CT image. Normal abdominal organ size and position were assessed, and topographic relationships among organs were ascertained. CONCLUSIONS AND CLINICAL RELEVANCE: The data obtained provide some reference standards for normal abdominal organ size and position in ringed seals. This information may aid researchers of future physiologic and clinical studies in this species.

Abdomen↗
PubMed2006

A systematic review of the diagnostic accuracy of provocative tests of the neck for diagnosing cervical radiculopathy.

Clinical provocative tests of the neck, which position the neck and arm inorder to aggravate or relieve arm symptoms, are commonly used in clinical practice in patients with a suspected cervical radiculopathy. Their diagnostic accuracy, however, has never been examined in a systematic review. A comprehensive search was conducted in order to identify all possible studies fulfilling the inclusion criteria. A study was included if: (1) any provocative test of the neck for diagnosing cervical radiculopathy was identified; (2) any reference standard was used; (3) sensitivity and specificity were reported or could be (re-)calculated; and, (4) the publication was a full report. Two reviewers independently selected studies, and assessed methodological quality. Only six studies met the inclusion criteria, which evaluated five provocative tests. In general, Spurling's test demonstrated low to moderate sensitivity and high specificity, as did traction/neck distraction, and Valsalva's maneuver. The upper limb tension test (ULTT) demonstrated high sensitivity and low specificity, while the shoulder abduction test demonstrated low to moderate sensitivity and moderate to high specificity. Common methodological flaws included lack of an optimal reference standard, disease progression bias, spectrum bias, and review bias. Limitations include few primary studies, substantial heterogeneity, and numerous methodological flaws among the studies; therefore, a meta-analysis was not conducted. This review suggests that, when consistent with the history and other physical findings, a positive Spurling's, traction/neck distraction, and Valsalva's might be indicative of a cervical radiculopathy, while a negative ULTT might be used to rule it out. However, the lack of evidence precludes any firm conclusions regarding their diagnostic value, especially when used in primary care. More high quality studies are necessary in order to resolve this issue.

Diagnostic Tests, Routine↗
PubMed2006

A robust approach for the quantitation of viral concentration in an adenoviral vector-based human immunodeficiency virus vaccine by real-time quantitative polymerase chain reaction.

A real-time quantitative polymerase chain reaction (PCR)-based method was developed to measure the concentration of recombinant adenoviral vector genomes in purified virus bulks and final container samples of monovalent and multivalent human immunodeficiency virus (HIV) adenoviral vector vaccine candidates. This method, referred to as the genome quantitation assay (GQA), was optimized through a rigorous approach for evaluating PCR detection chemistries, designing a robust assay format, and establishing a properly calibrated reference standard. In addition, the use of a simplified lysis procedure, automated liquid transfer system, and parallel-line data analysis contribute to an accurate, precise, reliable, and high-throughput assay procedure that can be used for process monitoring, final formulation, and release of vaccine products. A variance component analysis study indicated that the GQA typically produces results with an interassay precision of less than 10% relative standard deviation (RSD), allowing generation of final results (average of three runs) with associated interassay precision of 6% RSD or less. The precision, accuracy, specificity, and robustness of the GQA demonstrate its utility for analytical characterization of a wide variety of viral vector- and DNA plasmid- based vaccines or gene therapy products. In addition, we also evaluated the Adenovirus Reference Standard generated by the Adenovirus Reference Material Working Group in the GQA to provide a common point-of-reference for our analytical method.

AIDS Vaccines↗
PubMed1999

Scaling cardiac structural data by body dimensions: a review of theory, practice, and problems.

Robust estimates of the "true" bivariate relationship between body size (X) and heart size (Y) have seldom been determined empirically. The removal of the covariate influence of body size from cardiac dimension variables facilitates both correct inter- or intra-group comparisons, and the construction of reference standards for normality. In the literature to date this "scaling" or normalisation of cardiac dimensions has been performed typically via a per-ratio standards method, (Y/X), with body surface area chosen as the size denominator. This review demonstrates that the per-ratio standards approach may be theoretically, mathematically, and empirically flawed. The most appropriate scaling procedure appears to be a curvilinear, allometric model of the general form Y = aXb. The cardiac dimension variable (Y) may be regressed upon the body size variable (X) to derive a power function ratio (Y/Xb) that is allegedly size-independent. The current consensus is that an estimate of fat-free mass (FFM) provides the most appropriate body size variable. In the scaling literature allometric modelling procedures have generally yielded FFM exponents (b) consistent with the theory of geometric similarity. We suggest that cardiac dimension data should be scaled by appropriate powers of FFM, derived from allometric modelling. However, despite the potential superiority of FFM as a scaling denominator, reference standards for normality based on FFM have not been developed or proposed. Future research should examine the robustness of the FFM-cardiac dimension relationship in large samples.

Body Constitution↗