Table 1.

Sensitivity and specificity of medicare claims to identify dementia and Alzheimer’s disease^a

1a. Dementiab
		ADAMS
		Yes	No	Total
Medicare claims						Raw %	Weighted %
	Yes	235	68	303	Sensitivity	85.5%	84.8%
					Specificity	85.9%	89.2%
	No	40	415	455	Positive predictive value	77.6%	56.0%
					Negative predictive value	91.2%	97.3%
	Total	275	483	758
1b. Alzheimer’s diseasec
		ADAMS
		Yes	No	Total
Medicare claims
	Yes	126	49	175	Sensitivity	61.5%	64.2%
					Specificity	91.1%	95.2%
	No	79	504	583	Positive predictive value	72.0%	58.3%
					Negative predictive value	86.4%	96.2%
	Total	205	553	758

ADAMS = Aging, Demographics and Memory Study.

^aAll types of Medicare claims records were used: inpatient, outpatient; part B physician supplier file; home health; Skilled Nursing Facility (SNF); hospice, and durable medical equipment. A code corresponding to Alzheimer’s disease or more generally dementia could appear in either the primary or secondary diagnosis position of a claim.

^bDementia was noted by a series of codes used in past work, including ICD-9-CM code 331.0, Alzheimer’s disease.

^cAlzheimer’s disease was noted by the presence of ICD-9-CM code 331.0.