Cluster Analysis Of Patients Research Articles

Detection of malingering and somatization using the Pain Symptom Ratings, 2nd Edition

The purpose of this study was to derive categories of pain patients on the basis of their responses to a questionnaire designed to differentially diagnose somatization and malingering. The Pain Symptom Ratings, 2nd Edition (PSR-2) was administered to 4279 individuals seeking compensation for personal injuries. A sample of 500 random response protocols was used as a control group. Cluster Analysis of patients' PSR-2 subscale scores revealed 12 stable patient clusters (i.e., patients with similar PSR-2 subscale score patterns). Discriminant analysis using patient cluster as the dependent variable and PSR-2 subscale scores as the predictors correctly classified individuals in the control group with 99.4% accuracy. Correct classification rates of other patient clusters ranged between 88.2% and 98.3%. The PSR-2 profiles of 3 of the patient clusters were identical to the control group (i.e., random response group), with the only difference being in the magnitude of their subscale scores. The tendency to minimize and magnify symptoms was clearly visible in 2 groups. The remaining groups varied significantly along the dimensions of pain severity, neurological symptoms, mood, catastrophic thinking, somatization, symptom magnification and treatment outcome.

Symptom classification in irritable bowel syndrome as a guide to treatment

Objective. The treatment of irritable bowel syndrome (IBS) remains unsatisfactory. There are no objective markers for diagnosis, and classification (currently based on symptoms) provides little insight into potential causes or optimal therapy. The aim of this study was to determine whether a Swedish classification of IBS based on cluster analysis of patients’ symptoms might provide a guide to successful treatment. Material and methods. Patients in a research clinic for IBS were classified according to criteria published by Ragnarsson & Bodemar (R&B) and also assessed independently by a clinician. Patients fulfilling the R&B criteria for subgroups 1 and 2 received specific treatments, either bulk laxatives or dietary treatment to reduce colonic fermentation, respectively. Patients who did not fit into these categories were given “best treatment” targeted at their predominant symptoms, but not limited in any way. Results before and after follow-up were assessed using a validated symptom-scoring scale. Results. Seventy-one successive patients were recruited, and the numbers falling into R&B subgroups 1 and 2 were 15 (21%), and 28 (39%), respectively, leaving 28 (39%) unclassified. Receiver operating characteristic plots showed that the criteria for separation into subgroups 1 and 2 correlated well with the clinician's assessment. After treatment, symptom scores for the whole group showed a significant improvement (p<0.0001), but results were significantly better in subgroups 1 and 2 than in those unclassified, even when allowance was made for a potential therapeutic placebo effect of 40%. Conclusion. The R&B classification provides a helpful guide to treatment in many cases of IBS.

Anpassungsstörungen – Die Erprobung eines neuen diagnostischen Konzepts in einem ambulanten psychosomatischen Setting

Diagnoses of adjustment disorders are frequent in clinical settings, although diagnostic criteria are not very reliable or valid. This has led to a neglection of this topic in research. This article presents and applies a new concept (Maercker et al., 2007) for diagnosing adjustment disorders. 96 patients of a psychosomatic policlinic were examined regarding their emotional well-being with a new questionnaire (Adjustment Disorder--New Module | ADNM). Furthermore, according to the new concept, adjustment disorders were assessed with a structured interview. Coping behaviour (CISS) as well as general self efficacy (SWE) in patients with scores within a normal range and patients with elevated scores in ADNM, respectively, were examined. The following statistical measures were used: cluster analysis, cross tables, non-metrical and metrical test procedures. The theory-guided evaluation of the ADNM questionnaire divided the whole sample into patients with elevated (49 %) and with normal (51 %) scores. A cluster analysis of patients with elevated scores showed two groups, so that a total of three groups were compared: patients with scores in a normal range; patients with elevated scores and a low number of symptoms; patients with elevated scores and a high number of symptoms. Patients with elevated scores showed significantly more emotion-oriented coping strategies (t = - 6.338; p = 0.000) and reported, referring to present stress, on being less able to cope with it (Z = - 4.445; p = 0.000). Patients with elevated scores and a high number of symptoms named more stress factors (Z = - 2.634; p = 0.008) and reported on being more impulsive and irritable (Z = - 3.406; p = 0.003). The comparison of the ADNM questionnaire and the clinical main diagnoses shows a separation between emotional and non-emotional disturbances according to ICD-10 (chi2(2, n = 96) = 6.928; p = 0.031). The results show that the ADNM questionnaire according to the new diagnostic concept of adjustment disorders (Maercker et al., 2007) identifies patients who experience a high degree of stress caused by adverse life events of life conditions. The ADNM reliably differentiates non-emotional from emotional ICD-10 diagnoses. Further studies should examine, whether the new concept as well as the questionnaire are able to assess adjustment disorders in a valid and reliable way.

Hepatology highlights

Hepatology highlights

FMRI temporal clustering analysis in patients with frequent interictal epileptiform discharges: Comparison with EEG-driven analysis

Temporal clustering analysis (TCA) is an exploratory data-driven technique that has been proposed for the analysis of resting fMRI to localise epileptiform activity without need for simultaneous EEG. Conventionally, fMRI of epileptic activity has been limited to those patients with subtle clinical events or frequent interictal epileptiform EEG discharges, requiring simultaneous EEG recording, from which a linear model is derived to make valid statistical inferences from the fMRI data. We sought to evaluate TCA by comparing the results with those of EEG correlated fMRI in eight selected cases. Cases were selected with clear epileptogenic localisation or lateralisation on the basis of concordant EEG and structural MRI findings, in addition to concordant activations seen on EEG-derived fMRI analyses. In three, areas of activation were seen with TCA but none corresponding to the electro-clinical localisation or activations obtained with EEG driven analysis. Temporal clusters were closely coincident with times of maximal head motion. We feel this is a serious confound to this approach and recommend that interpretation of TCA that does not address motion and physiological noise be treated with caution. New techniques to localise epileptogenic activity with fMRI alone require validation with an appropriate independent measure. In the investigation of interictal epileptiform activity, this is best done with simultaneous EEG recording.

Cluster Analysis of Patients With Ocular Surface Disease, Blepharitis,and Dry Eye

To develop a classification system for blepharitis and dry eye based on a classification-tree model of a large group of subjects who were given a variety of objective physiologic tests. We evaluated 513 subjects, some healthy and some with blepharitis and dry eye,with tests for tear volume, tear flow, and tear turnover and the Schirmer test for dry eye. Meibomian gland function was evaluated by meibomian gland lipid expression for lipid volume and lipid viscosity, evaporation, and eyelid transillumination for meibomian gland drop out. We subjected these data to cluster analysis and formulated a classification tree. The outcome measure of this study was the statistically valid groups of subjects with and without ocular surface symptoms identified by their physiologic characteristics. Cluster analysis most successfully grouped subjects by initially dividing them into 2 groups based on the presence or absence of gland drop out and then by lipid viscosity and volume, Schirmer test results, and evaporation. The analysis created 9 categories. This division created an objective classification system that was found to have clinical relevance. Normal subjects were distributed across several groups. Using a classification tree, blepharitis and dry eye can be classified with objective physiologic tests into clinically relevant groups that have common characteristics. The analysis establishes the central role of meibomian gland dysfunction in blepharitis and demonstrates the diverse characteristics of the normal population.