Comparison of diagnostic validity of two autism rating scales for suspected autism in a large Chinese sample

Table 1 The description of autism behavior checklist and childhood autism rating scale

Variables	Mean	SD	Kurtosis	Skewness	Cronbach's α	AUC	AUC (95%CI)
ABC	70.05	1.19	0.39	-0.04	0.426	0.768	0.727-0.805
CARS	35.72	4.10	1.39	0.99	0.772	0.846	0.810-0.877

SD: Standard deviation; ABC: Autism behavior checklist; CARS: Childhood autism rating scale; AUC: Area under curve; CI: Confidence interval.

Table 2 The cutoff points and corresponding sensitivity and specificity of autism behavior checklist and childhood autism rating scale

Criterion	Sensitivity	95%CI	Specificity	95%CI	+LR	-LR
ABC
> 62	80.45	76.2-84.2	58.67	46.7-69.9	1.95	0.33
> 63	77.94	73.6-81.9	61.33	49.4-72.4	2.02	0.36
> 64	76.19	71.7-80.3	65.33	53.5-76.0	2.2	0.36
> 65	73.68	69.1-77.9	68	56.2-78.3	2.3	0.39
> 66	72.18	67.5-76.5	69.33	57.6-79.5	2.35	0.4
> 67	68.17	63.4-72.7	76	64.7-85.1	2.84	0.42
> 68	63.41	58.5-68.1	80	69.2-88.4	3.17	0.46
> 69	58.9	53.9-63.8	82.67	72.2-90.4	3.4	0.5
> 72	48.12	43.1-53.1	82.67	72.2-90.4	2.78	0.63
> 73	44.36	39.4-49.4	84	73.7-91.4	2.77	0.66
> 74	41.1	36.2-46.1	85.33	75.3-92.4	2.8	0.69
CARS
> 30	92.98	90.0-95.3	40	28.9-52.0	1.55	0.18
> 31	85.46	81.6-88.8	60	48.0-71.1	2.14	0.24
> 32	78.7	74.3-82.6	76	64.7-85.1	3.28	0.28
> 33	68.42	63.6-73.0	90.67	81.7-96.2	7.33	0.35
> 34	57.64	52.6-62.5	94.67	86.9-98.5	10.81	0.45
> 35	33.33	28.7-38.2	97.33	90.7-99.7	12.5	0.68
> 36	29.07	24.7-33.8	98.67	92.8-100.0	21.8	0.72
> 37	1	0.3-2.5	98.67	92.8-100.0	0.75	1

ABC: Autism behavior checklist; CARS: Childhood autism rating scale; CI: Confidence interval; +LR: Positive likelihood ratio; -LR: Negative likelihood ratio.

Table 3 The positive predictive value and negative predictive value for autism behavior checklist and childhood autism rating scale

Variables	ABC	CARS	χ2 value	P value
PPV	93%	95%	1.048	0.306
NPV	32%	40%	2.243	0.134

ABC: Autism behavior checklist; CARS: Childhood autism rating scale; PPV: Positive predictive value; NPV: Negative predictive value.