Water displacement leg volumetry in clinical studies - A discussion of error sources

<p>Abstract</p> <p>Background</p> <p>Water displacement leg volumetry is a highly reproducible method, allowing the confirmation of efficacy of vasoactive substances. Nevertheless errors of its execution and the selection of unsuitable patients are likely to negatively affect the outcome of clinical studies in chronic venous insufficiency (CVI).</p> <p>Discussion</p> <p>Placebo controlled double-blind drug studies in CVI were searched (Cochrane Review 2005, MedLine Search until December 2007) and assessed with regard to efficacy (volume reduction of the leg), patient characteristics, and potential methodological error sources. Almost every second study reported only small drug effects (≤ 30 mL volume reduction). As the most relevant error source the conduct of volumetry was identified. Because the practical use of available equipment varies, volume differences of more than 300 mL - which is a multifold of a potential treatment effect - have been reported between consecutive measurements. Other potential error sources were insufficient patient guidance or difficulties with the transition from the Widmer CVI classification to the CEAP (Clinical Etiological Anatomical Pathophysiological) grading.</p> <p>Summary</p> <p>Patients should be properly diagnosed with CVI and selected for stable oedema and further clinical symptoms relevant for the specific study. Centres require a thorough training on the use of the volumeter and on patient guidance. Volumetry should be performed under constant conditions. The reproducibility of short term repeat measurements has to be ensured.</p

Estudo da confiabilidade e validade da utilização do hidropletismômetro para medida de edema no tornozelo Study of the reliability and validity of the water plethysmographer for use in measurement of the edema at the ankle/foot

Instrumentos confiáveis e válidos são necessários para avaliar a efetividade das técnicas de reabilitação. O objetivo deste estudo foi avaliar a confiabilidade e a validade do Hidropletismômetro. Quatorze sujeitos com idade entre 18 e 59 anos foram selecionados para participar do estudo. Os tornozelos foram avaliados por dois examinadores treinados com o Hidropletismômetro. Três medidas de cada tornozelo foram obtidas pelos examinadores de forma aleatória para investigar a confiabilidade intra e inter-examinadores. Foram também obtidas vinte e seis medidas com o Hidropletismômetro e comparadas com as medidas obtidas com o Deslocador de Água considerado "padrão ouro", através de provetas de vidro graduadas de 10 ml a 1000 ml. A confiabilidade intra e inter-examinadores foi realizada através do Coeficiente de Correlação Intraclasse (CCI) e a validade através do teste t pareado. O Coeficiente de Correlação de Pearson foi utilizado para estabelecer a associação entre os dois instrumentos. Os dados demonstraram níveis de confiabilidade intra e inter-examinadores com (CCI)3,1 = 0,99 e (CCI)3,2 = 0,99, respectivamente. Nenhuma diferença foi encontrada entre as medidas obtidas com o Hidropletismômetro e as obtidas com as provetas (p=0,404). A Correlação de Coeficiente de Pearson mostrou alta magnitute e nível de significância entre as medidas (r=1,0; p<0,0001). Os resultados evidenciaram que o Hidropletismômetro é um instrumento confiável e válido para medida de volume do tornozelo/pé.<br>Reliable and valid instruments are necessary to evaluate the effectiveness of the rehabilitation techniques.The objective this study was to evaluate the reliability and the validity of the water plethysmography. Fourteen subjects between the ages of 18 and 59 years were selected to participate in the study. Ankles were assessed by two trained examiners with the water plethysmography. Three measures of each ankle were obtained by the two investigators to evaluate intra- and inter-raters reliability. Twenty-six measures were obtained with the water plethysmography and compared with measurements obtained by graduated cylinders from 10 to 1000 ml, water displacement device (gold standart). Intraclass correlation coefficients (ICCs) evaluated intra- and inter-raters reliability, whereas paired Student t-tests and Pearson's correlation coefficients were used to establish validity of the water plethysmography.The results demonstrated excellent intra- and inter-rater reliability levels with levels with CCI3,1=0.99 and CCI3,2=0.99 respectively. No differences were found between the measures obtained with the water plethysmography compared to those of the water displacement device (p=0.40). Pearson's correlation coefficient showed a high magnitude and significance level between the measures (r=1,0; p<0.0001).The findings demonstrated that the water plethysmography is a reliable and valid instrument for measuring ankle/foot volume