Comparison of three alternative methods for analysis of equine Faecal Egg Count Reduction Test data.
Abstract: The Faecal Egg Count Reduction Test (FECRT) is the most widely used method of assessing the efficacy of anthelmintics, and is the only in vivo technique currently approved for use with horses. Equine Faecal Egg Count (FEC) data are frequently characterised by a low mean, high variability, small sample size and frequent zero count observations. Accurate analysis of the data therefore depends on the use of an appropriate statistical technique. Analyses of simulated FECRT data by methods based on calculation of the empirical mean and variance, non-parametric bootstrapping, and Markov chain Monte Carlo (MCMC) are compared. The MCMC method consistently outperformed the other methods, independently of the distribution from which the data were generated. Bootstrapping produced notional 95% confidence intervals containing the true parameter as little as 40% of the time with sample sizes of less than 50. Analysis of equine FECRT data yielded inconclusive results in 53 of 63 (84%) datasets, suggesting that the routine use of prior sample size calculations should be adopted to ensure sufficient data are collected. The authors conclude that computationally intensive parametric methods such as MCMC be used for analysis of FECRT data with sample sizes of less than 50, in order to avoid erroneous inference about the true efficacy of anthelmintics in the field.
Publication Date: 2009-12-03 PubMed ID: 19962203DOI: 10.1016/j.prevetmed.2009.11.009Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The study compares three different statistical analysis methods for the Faecal Egg Count Reduction Test (FECRT) data in horses. The researchers find the Markov chain Monte Carlo method to be the most effective in these situations, especially when sample sizes are less than 50.
Introduction
- The Faecal Egg Count Reduction Test (FECRT) is a common method for assessing the efficiency of anthelmintics, a type of drug used to expel parasitic worms, in horses. The test analyzes equine faecal egg count (FEC), which is often characterized by a low mean, high variability, small sample size, and frequent zero count observations. As such, accurate analysis of this data necessitates an appropriate statistical technique.
Methods Compared
- In this research, three statistical analysis methods were compared: empirical mean and variance calculation, non-parametric bootstrapping, and Markov chain Monte Carlo (MCMC). The latter is a method for approximating the distribution of unknown parameters through simulation, which improves predictions based on observed data.
Outcomes
- The results showed that the MCMC method consistently outperformed the other two methods, regardless of the distribution from which the data were generated.
- Bootstrapping, another resampling technique, produced notional 95% confidence intervals that contained the true parameter only about 40% of the time when the sample sizes were less than 50.
Conclusions
- Applying these methods to equine FECRT data, 84% of the datasets (53 out of 63) showed inconclusive results. This outcome suggests that prior sample size calculations should be routinely used to ensure that sufficient data is collected.
- The authors concluded that computationally intensive parametric methods, like MCMC, should be used to analyze FECRT data when dealing with small sample sizes under 50. This would help to avoid misunderstandings about the true efficacy of anthelmintics.
Cite This Article
APA
Denwood MJ, Reid SW, Love S, Nielsen MK, Matthews L, McKendrick IJ, Innocent GT.
(2009).
Comparison of three alternative methods for analysis of equine Faecal Egg Count Reduction Test data.
Prev Vet Med, 93(4), 316-323.
https://doi.org/10.1016/j.prevetmed.2009.11.009 Publication
Researcher Affiliations
- Boyd Orr Centre for Population and Ecosystem Health, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Glasgow, UK. m.denwood@vet.gla.ac.uk
MeSH Terms
- Animals
- Anthelmintics / therapeutic use
- Feces / parasitology
- Helminthiasis, Animal / drug therapy
- Helminthiasis, Animal / epidemiology
- Horse Diseases / drug therapy
- Horses
- Netherlands / epidemiology
- Parasite Egg Count / methods
- Parasite Egg Count / veterinary
Citations
This article has been cited 12 times.- Walker M, Freitas LT, Halder JB, Brack M, Keiser J, King CH, Levecke B, Ai-Lian Lim Y, Pieri O, Sow D, Stothard JR, Webster JP, Zhou XN, Terry RF, Guérin PJ, Basáñez MG. Improving anthelmintic treatment for schistosomiasis and soil-transmitted helminthiases through sharing and reuse of individual participant data. Wellcome Open Res 2022;7:5.
- Morgan ER, Lanusse C, Rinaldi L, Charlier J, Vercruysse J. Confounding factors affecting faecal egg count reduction as a measure of anthelmintic efficacy. Parasite 2022;29:20.
- Wang C, Torgerson PR, Kaplan RM, George MM, Furrer R. Modelling anthelmintic resistance by extending eggCounts package to allow individual efficacy. Int J Parasitol Drugs Drug Resist 2018 Dec;8(3):386-393.
- Odden A, Denwood MJ, Stuen S, Robertson LJ, Ruiz A, Hamnes IS, Hektoen L, Enemark HL. Field evaluation of anticoccidial efficacy: A novel approach demonstrates reduced efficacy of toltrazuril against ovine Eimeria spp. in Norway. Int J Parasitol Drugs Drug Resist 2018 Aug;8(2):304-311.
- Love JW, Kelly LA, Lester HE, Nanjiani I, Taylor MA, Robertson C. Investigating anthelmintic efficacy against gastrointestinal nematodes in cattle by considering appropriate probability distributions for faecal egg count data. Int J Parasitol Drugs Drug Resist 2017 Apr;7(1):71-82.
- Peña-Espinoza M, Thamsborg SM, Denwood MJ, Drag M, Hansen TV, Jensen VF, Enemark HL. Efficacy of ivermectin against gastrointestinal nematodes of cattle in Denmark evaluated by different methods for analysis of faecal egg count reduction. Int J Parasitol Drugs Drug Resist 2016 Dec;6(3):241-250.
- Geurden T, Chartier C, Fanke J, di Regalbono AF, Traversa D, von Samson-Himmelstjerna G, Demeler J, Vanimisetti HB, Bartram DJ, Denwood MJ. Anthelmintic resistance to ivermectin and moxidectin in gastrointestinal nematodes of cattle in Europe. Int J Parasitol Drugs Drug Resist 2015 Dec;5(3):163-71.
- Fischer JK, Hinney B, Denwood MJ, Traversa D, von Samson-Himmelstjerna G, Clausen PH. Efficacy of selected anthelmintic drugs against cyathostomins in horses in the federal state of Brandenburg, Germany. Parasitol Res 2015 Dec;114(12):4441-50.
- Falzon LC, van Leeuwen J, Menzies PI, Jones-Bitton A, Sears W, Jansen JT, Peregrine AS. Comparison of calculation methods used for the determination of anthelmintic resistance in sheep in a temperate continental climate. Parasitol Res 2015 Apr;114(4):1631-43.
- Matthews JB. Anthelmintic resistance in equine nematodes. Int J Parasitol Drugs Drug Resist 2014 Dec;4(3):310-5.
- Falzon LC, van Leeuwen J, Menzies PI, Jones-Bitton A, Sears W, Jansen JT, Peregrine AS. Comparison of calculation methods used for the determination of anthelmintic resistance in sheep in a temperate continental climate. Parasitol Res 2014 Jun;113(6):2311-22.
- Corbett CJ, Love S, Moore A, Burden FA, Matthews JB, Denwood MJ. The effectiveness of faecal removal methods of pasture management to control the cyathostomin burden of donkeys. Parasit Vectors 2014 Jan 24;7:48.
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