Table 2.

Comparison of gastroscopic sampling methods for diagnosing squamate gastric cryptosporidiosis in eastern indigo snakes (Drymarchon couperi)

	n	κ	Sensitivity	Specificity	PPV	NPV
			(95% CI)	(95% CI)	(95% CI)	(95% CI)
Organism and lesion	70	0.588	100.00%	62.50%	35.00%	100%
			(88.43–100.00%)	(45.80–77.27%)	(26.52–44.55%)
Lesions only	70	0.340	75.81%	87.50%	55.05%	94.71%
			(63.26–85.78%)	(47.35–99.68%)	(16.30–88.51%)	(91.47–96.76%)

Organism and lesion = comparison of C. serpentis qPCR on gastric tissue collected by gastroscopy versus histologic analysis of gastric tissue collected by gastroscopy where cryptosporidial organisms were visualized; Lesions only = comparison of C. serpentis qPCR on gastric tissue collected by gastroscopy versus histologic analysis of gastric tissue collected by gastroscopy where pathologic changes consistent with cryptosporidiosis were present regardless if cryptosporidial organisms were seen; n = number of snakes sampled; κ = Cohen's kappa coefficient; 95% CI = 95% confidence interval. Calculations were made based on the prevalence of 16.8% within the collection. Guidelines for interpreting κ values: very good agreement, 0.81–1.00; good agreement, 0.61–0.80; moderate agreement, 0.41–0.60; fair agreement, 0.21–0.40; and poor agreement, less than 0.20