The Veterinary Journal 200 (2014) 6–7
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
Guest Editorial
Statistics and epidemiological studies: Emerging fields in veterinary research and medicine
In a recent issue of The Veterinary Journal, Dr. Marianne Depecker and her colleagues describe an important field study where not less than 138 French Standardbred horses were investigated (Depecker et al., 2014). All horses underwent a thorough clinical examination, upper and lower airway endoscopy as well as left and right lung side bronchoalveolar lavage (BAL). The authors applied a standardised BAL collection procedure and separately analysed samples collected from the right and the left lungs. A complete BAL fluid analysis including total and differential cell counts was then performed. Thorough analysis of the results, and in particular a comparison of left vs. right lungs, evidenced differences between lung sides with a higher proportion of horses showing cytological signs of exercise-induced pulmonary haemorrhage (EIPH) or/and inflammatory airway disease (IAD) in BAL fluid from the right lung side (Depecker et al., 2014). Moreover, the application of two cut-off levels showed that the proportion of IAD-affected horses might considerably change the prevalence of IAD and also modify agreement between cytological results of both lungs. This thoroughly conducted field study reflects several important trends in veterinary respiratory research and medicine. Firstly, research performed under ‘controlled’ conditions shows its limitations and poorly reflects natural variability. Previous comparisons between left and right BAL fluid samples performed on small numbers of ‘research horses’ have not shown important lung side related differences (Sweeney et al., 1992; Jean et al., 2011). If both lung sides underwent BAL, samples were pooled. The findings of Depecker et al. (2014) suggest that left and right lung BAL samples should be considered separately. Secondly, rigorous sampling, processing and analytical procedures are seen to be increasingly important. Indeed, dilution techniques aimed at standardising marker concentrations in BAL fluid (Rennard et al., 1985; Kirschvink et al., 2001) have progressively been abandoned and replaced by well-defined collection protocols (Robinson, 2001). Consequently, excellence in technical skills and accuracy is critical. Thirdly, the appropriate use of statistical analyses becomes highly important and more challenging. Depecker et al. (2014) have shown that IAD prevalence considerably changes as a function of the cut-off used (Robinson, 2003; Richard et al., 2010). These results as well as those of the between-lung agreements described in the study illustrate the central contribution of statistics in modern veterinary research. Fig. 1 illustrates the evolution since 1980 of PubMed referenced publications dealing with BAL collection in companion animals (i.e. dogs and cats), production animals (i.e. cattle, small ruminants, http://dx.doi.org/10.1016/j.tvjl.2014.01.004 1090-0233/Ó 2014 Elsevier Ltd. All rights reserved.
Fig. 1. Evolution of PubMed-referenced publications reporting bronchoalveolar lavage fluid data in animals between 1980 and 2012.
pigs) and horses. Whatever the species, respiratory research in veterinary medicine constantly progresses and increases in terms of scientific output. Moreover, a trend towards field investigations has appeared, meaning that appropriate epidemiological and statistical approaches are required. Future animal health professionals will need more and more skills in these fields and educators must therefore consider urgently the very real demand for these requirements in the veterinary undergraduate curriculum. Acknowledgement Alice Foulon, a veterinary student at the University of Namur, is gratefully acknowledged for her help in searching the publications dealing with bronchoalveolar lavage in animal species. Nathalie Kirschvink Integrated Veterinary Research Unit, Department of Veterinary Medicine, University of Namur, 61 rue de Bruxelles, B-5000 Namur, Belgium E-mail address: [email protected]
Guest Editorial / The Veterinary Journal 200 (2014) 6–7
References Depecker, M., Richard, E.A., Pitel, P.-H., Fortier, G., Leleu, C., Couroucé-Malblanc, A., 2014. Bronchoalveolar lavage fluid in Standardbred racehorses: Influence of unilateral/bilateral profiles and cut-off values on lower airway disease diagnosis. The Veterinary Journal 199, 150–156. Jean, D., Vrins, A., Beauchamp, G., Lavoie, J.P., 2011. Evaluation of variations in bronchoalveolar lavage fluid in horses with recurrent airway obstruction. American Journal of Veterinary Research 72, 838–842. Kirschvink, N., Fiévez, L., Dogné, S., Bureau, F., Art, T., Lekeux, P., 2001. Comparison of inulin with urea as dilutional markers of bronchoalveolar lavage in healthy and heaves-affected horses. Veterinary Research 32, 145–154. Rennard, S.I., Basset, G., Lecossier, D., O’Donnell, K.M., Pinkston, P., Martin, P.G., Crystal, R.G., 1985. Estimation of volume of epithelial lining fluid recovered by
7
lavage using urea as marker of dilution. Journal of Applied Physiology 60, 532– 538. Richard, E.A., Fortier, G., Lekeux, P., van Erck, E., 2010. Laboratory findings in respiratory fluids of the poorly-performing horse. The Veterinary Journal 185, 115–122. Robinson, N.E., 2001. International Workshop on Equine Chronic Airway Disease. Michigan State University 16–18 June 2000. Equine Veterinary Journal 33, 5–19. Robinson, N.E., 2003. Inflammatory airway disease: Defining the syndrome. Conclusions of the Havermeyer Workshop. Equine Veterinary Education 15, 61–63. Sweeney, C.R., Rossier, Y., Ziemer, E.L., Lindborg, S., 1992. Effects of lung site and fluid volume on results of bronchoalveolar lavage fluid analysis in horses. American Journal of Veterinary Research 53, 1376–1379.
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
Guest Editorial
Statistics and epidemiological studies: Emerging fields in veterinary research and medicine
In a recent issue of The Veterinary Journal, Dr. Marianne Depecker and her colleagues describe an important field study where not less than 138 French Standardbred horses were investigated (Depecker et al., 2014). All horses underwent a thorough clinical examination, upper and lower airway endoscopy as well as left and right lung side bronchoalveolar lavage (BAL). The authors applied a standardised BAL collection procedure and separately analysed samples collected from the right and the left lungs. A complete BAL fluid analysis including total and differential cell counts was then performed. Thorough analysis of the results, and in particular a comparison of left vs. right lungs, evidenced differences between lung sides with a higher proportion of horses showing cytological signs of exercise-induced pulmonary haemorrhage (EIPH) or/and inflammatory airway disease (IAD) in BAL fluid from the right lung side (Depecker et al., 2014). Moreover, the application of two cut-off levels showed that the proportion of IAD-affected horses might considerably change the prevalence of IAD and also modify agreement between cytological results of both lungs. This thoroughly conducted field study reflects several important trends in veterinary respiratory research and medicine. Firstly, research performed under ‘controlled’ conditions shows its limitations and poorly reflects natural variability. Previous comparisons between left and right BAL fluid samples performed on small numbers of ‘research horses’ have not shown important lung side related differences (Sweeney et al., 1992; Jean et al., 2011). If both lung sides underwent BAL, samples were pooled. The findings of Depecker et al. (2014) suggest that left and right lung BAL samples should be considered separately. Secondly, rigorous sampling, processing and analytical procedures are seen to be increasingly important. Indeed, dilution techniques aimed at standardising marker concentrations in BAL fluid (Rennard et al., 1985; Kirschvink et al., 2001) have progressively been abandoned and replaced by well-defined collection protocols (Robinson, 2001). Consequently, excellence in technical skills and accuracy is critical. Thirdly, the appropriate use of statistical analyses becomes highly important and more challenging. Depecker et al. (2014) have shown that IAD prevalence considerably changes as a function of the cut-off used (Robinson, 2003; Richard et al., 2010). These results as well as those of the between-lung agreements described in the study illustrate the central contribution of statistics in modern veterinary research. Fig. 1 illustrates the evolution since 1980 of PubMed referenced publications dealing with BAL collection in companion animals (i.e. dogs and cats), production animals (i.e. cattle, small ruminants, http://dx.doi.org/10.1016/j.tvjl.2014.01.004 1090-0233/Ó 2014 Elsevier Ltd. All rights reserved.
Fig. 1. Evolution of PubMed-referenced publications reporting bronchoalveolar lavage fluid data in animals between 1980 and 2012.
pigs) and horses. Whatever the species, respiratory research in veterinary medicine constantly progresses and increases in terms of scientific output. Moreover, a trend towards field investigations has appeared, meaning that appropriate epidemiological and statistical approaches are required. Future animal health professionals will need more and more skills in these fields and educators must therefore consider urgently the very real demand for these requirements in the veterinary undergraduate curriculum. Acknowledgement Alice Foulon, a veterinary student at the University of Namur, is gratefully acknowledged for her help in searching the publications dealing with bronchoalveolar lavage in animal species. Nathalie Kirschvink Integrated Veterinary Research Unit, Department of Veterinary Medicine, University of Namur, 61 rue de Bruxelles, B-5000 Namur, Belgium E-mail address: [email protected]
Guest Editorial / The Veterinary Journal 200 (2014) 6–7
References Depecker, M., Richard, E.A., Pitel, P.-H., Fortier, G., Leleu, C., Couroucé-Malblanc, A., 2014. Bronchoalveolar lavage fluid in Standardbred racehorses: Influence of unilateral/bilateral profiles and cut-off values on lower airway disease diagnosis. The Veterinary Journal 199, 150–156. Jean, D., Vrins, A., Beauchamp, G., Lavoie, J.P., 2011. Evaluation of variations in bronchoalveolar lavage fluid in horses with recurrent airway obstruction. American Journal of Veterinary Research 72, 838–842. Kirschvink, N., Fiévez, L., Dogné, S., Bureau, F., Art, T., Lekeux, P., 2001. Comparison of inulin with urea as dilutional markers of bronchoalveolar lavage in healthy and heaves-affected horses. Veterinary Research 32, 145–154. Rennard, S.I., Basset, G., Lecossier, D., O’Donnell, K.M., Pinkston, P., Martin, P.G., Crystal, R.G., 1985. Estimation of volume of epithelial lining fluid recovered by
7
lavage using urea as marker of dilution. Journal of Applied Physiology 60, 532– 538. Richard, E.A., Fortier, G., Lekeux, P., van Erck, E., 2010. Laboratory findings in respiratory fluids of the poorly-performing horse. The Veterinary Journal 185, 115–122. Robinson, N.E., 2001. International Workshop on Equine Chronic Airway Disease. Michigan State University 16–18 June 2000. Equine Veterinary Journal 33, 5–19. Robinson, N.E., 2003. Inflammatory airway disease: Defining the syndrome. Conclusions of the Havermeyer Workshop. Equine Veterinary Education 15, 61–63. Sweeney, C.R., Rossier, Y., Ziemer, E.L., Lindborg, S., 1992. Effects of lung site and fluid volume on results of bronchoalveolar lavage fluid analysis in horses. American Journal of Veterinary Research 53, 1376–1379.
