Agreement and disagreement between pathologists in histological diagnosis

Irreproducibility of the activity and chronicity indices limits their utility in the management of lupus nephritis. Lupus Nephritis Collaborative Study Group

Histological indices of renal pathology in lupus nephritis have been proposed as prognostic signs and as a method to quantitate therapeutic response. We tested the reproducibility of the activity (AI) and chronicity indices (CI) in the renal biopsies from 83 patients with lupus nephritis, enrolled in a controlled therapeutic trial. The AI/CI were calculated separately by four renal pathologists using published criteria. Pair-wise Spearman's rank correlation coefficient was used to examine the relationship among the scores of the four raters, and their degree of reproducibility was evaluated using the coefficient of reliability. The mean CI scores ranged from 2.84 to 4.61, and the mean AI ranged from 9.64 to 12.89. The correlation among the different pathologist's scores ranged from 0.44 to 0.63 for the AI and 0.60 to 0.76 for the CI. One pathologist (M.M.S.) rated the biopsies twice, and the correlation between the two ratings was 0.58 for the AI and 0.74 for the CI. Thus, the AI and CI calculated by different pathologists and the temporally separate observations of a single observer were only moderately correlated. The reproducibility of a single rating was low, showing a reliability coefficient of 0.48 for the AI and 0.57 for the CI. The low reliability coefficient suggests that the variability among pathologists was the result of interpretative differences. We conclude that the AI/CI are too subjective to be used as therapeutic guides or as prognosticators.

Predictive value of renal pathology in diffuse proliferative lupus glomerulonephritis. Lupus Nephritis Collaborative Study Group

We tested the value of the activity (AI) and chronicity (CI) indices devised by Austin et al as predictors of outcome in lupus patients with diffuse proliferative glomerulonephritis (DPGN). Four renal pathologists independently scored the AI and CI on 84 renal biopsy specimens from patients with lupus DPGN followed for 109 +/- 74 weeks (mean +/- SD), and the mean score was compared to the development of renal failure and to adverse outcome (combined data for renal failure, death and predefined clinical stop points). Receiver operator characteristic curves were derived from a series of 2 x 2 tables in which one variable was renal failure or adverse outcome and the other variable was AI or CI dichotomized by a cut-off point. Over the entire range (0 to 10) of the CI there was no value that separated patients who developed renal failure from those who did not. The ROC curve analysis indicated that the sensitivity and specificity of the CI were too low to allow it to function as a good test. Once patients entering renal failure were identified, the mean CI approached but did not reach a significant difference when compared to the mean CI of those who did not go into renal failure (4.38 +/- 0.42, mean +/- SE vs. 3.19 +/- 0.23, P = 0.0620). The CI did not predict the adverse clinical outcomes. There was no cut-off value of the CI which separated patients who had an adverse outcome from those who did not, and this result was confirmed by ROC analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative immunocytochemistry by digital image analysis: application to toxicologic pathology

Recent advances in immunocytochemical techniques allow the localization of specific antigens in tissue sections. The work reported here attempts to evaluate the application of antibody-labeled, disease-related protein, followed by microscopy and computerized image analysis. Using an experimental anti-tumor, polyclonal antibody (anti-oncomodulin) as a model, various tissues were prepared for light microscope immunocytochemistry. Sections were incubated with primary antibody, then biotinylated secondary antibody. This was followed by incubation with avidin-biotin-peroxidase (ABC method). Marker was visualized by the presence of precipitated diaminobenzidine. Samples were evaluated using a Zeiss/Kontron IBAS I & II semi-automatic digital image analysis system. Statistical analyses were performed on output data. Results demonstrated the localization and determined optical density of immunolabel. Statistical comparisons showed significant differences between control and experimental sections. The practical application of these combined techniques provides the toxicologic pathologist with a powerful tool for accurate and objective determination of the location and relative amount of selected proteins in normal and abnormal tissues.

Measuring repeatability and validity of histological diagnosis--a brief review with some practical examples

Evaluation of histological diagnosis requires an index of agreement (to measure repeatability and validity) together with a method of assessing bias. Cohen's kappa statistic appears to be the most suitable tool for measuring levels of agreement, which if unsatisfactory may be caused by bias. Further study of bias is possible by examining levels of agreement for each diagnostic category or by searching for categories of disagreement in which more observations occur than would be expected by chance alone. This article gives reasons for choosing the kappa statistic, with examples illustrating its calculation and the investigation of bias.

Invasive squamous cell carcinoma of the uterine cervix. II. Reproducibility of a histopathologic malignancy grading system

A histopathologic malignancy grading system for invasive squamous carcinoma of the uterine cervix has previously been presented. The grading results in a total malignancy point value for every patient (range 8-24). This score has been proven to have a significant prognostic value for the individual patient. The inter-observer reproducibility of this system has been examined by two pathologists, on the pretreatment biopsies of 100 patients and the intra-observer reproducibility on 190 patients (observer one) and on 100 patients (observer two). These biopsies were estimated twice and three times, respectively, without knowledge of former results and at an interval of 2 to 6 months. The inter-observer correlation coefficient was 0.54, the intra-observer correlation coefficients 0.94 and 0.74, respectively.

Quality control in histopathology and diagnostic cytology

The need for quality control in diagnostic histopathology and cytology is analysed together with a discussion of previously reported experience in this field. The philosophical and mathematical inferences of this type of exercise are debated also in relationship to personally observed experiences in respect of uterine cervical cytology and histology. The desirability of methods of monitoring of diagnostic quality and of obtaining quality improvement are emphasized and suggestions made regarding the techniques most suited to these objectives.