Introduction The use of computer-generated three-dimensional (3D) anatomical

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Eighteen patients with definite, untreated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) of chronic progressive (nine patients) or relapsing course (nine patients) were randomized prospectively to receive 10 plasma-exchange (PE) or sham plasma-exchange (SPE) treatments over 4 weeks in a double-blind trial. After a wash-out period of 5 weeks or when they returned to baseline scores, patients were crossed over to the alternate treatments. Neurological function was assessed serially using a quantitative neurological disability score (NDS), a functional clinical grade (CG) and grip strength (GS) measurements. Electrophysiological studies were done at the beginning and end of each treatment. A primary 'intention to treat' analysis showed significant improvement with PE in all clinical outcome measures: NDS by 38 points, P < 0.001; CG by 1.6 points, P < 0.001; GS by +13 kg, P < 0.003 and in selected electrophysiological measurements, sigma proximal CMAP, P < 0.01; sigma motor conduction velocities, P < 0.006; sigma distal motor latencies, P < 0.01. Fifteen patients completed the trial and of those, 12 patients (80%) improved substantially with PE; i.e. five out of seven patients with chronic progressive course and seven out of eight patients with relapsing CIDP improved. There were three drop-outs; one patient lost venous access; one patient suffered a stroke and one patient left the trial to receive open treatment elsewhere. The improvement in motor functions correlated with the electrophysiological data, i.e. with improved motor conduction velocities and reversal of conduction block. Eight of 12 PE responders (66%) relapsed within 7-14 days after stopping PE. All improved with subsequent open label PE; all but two patients required long-term immunosuppressive drug therapy for stabilization. The PE non-responders improved with prednisone. We conclude that PE is a very effective adjuvant therapy for CIDP of both chronic progressive and relapsing course; concurrent immunosuppressive drug treatment is required. Exchange treatments should be given two to three times per week until improvement is established; the treatment frequency should then be tapered over several months.

CONTEXT Script concordance test (SCT) scores are intended to reflect respondents' competence in interpreting clinical data under conditions of uncertainty. The validity of inferences based on SCT scores has not been rigorously established.OBJECTIVES This study was conducted in order to develop a structured validity argument for the interpretation of test scores derived through use of the script concordance method. METHODSWe searched the PubMed, EMBASE and PsycINFO databases for articles pertaining to script concordance testing. We then reviewed these articles to evaluate the construct validity of the script concordance method, following an established approach for analysing validity data from five categories: content; response process; internal structure; relations to other variables, and consequences.RESULTS Content evidence derives from clear guidelines for the creation of authentic, ill-defined scenarios. High internal consistency reliability supports the internal structure of SCT scores. As might be expected, SCT scores correlate poorly with assessments of pure factual knowledge, in which correlations for more advanced learners are lower. The validity of SCT scores is weakly supported by evidence pertaining to examinee response processes and educational consequences.CONCLUSIONS Published research generally supports the use of SCT to assess the interpretation of clinical data under conditions of uncertainty, although specifics of the validity argument vary and require verification in different contexts and for particular SCTs. Our review identifies potential areas of further validity inquiry in all five categories of evidence. In particular, future SCT research might explore the impact of the script concordance method on teaching and learning, and examine how SCTs integrate with other assessment methods within comprehensive assessment programmes.

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