Table 3.

Dementia incidence rates (cumulative % and per 1000 person-years (PY)), overall and by age for patients ≥50 years old in VHA and KPW who did vs. did not initiate metformin within 6-months after HbA1c index

	VHA (n=112,845)			KPW (n=14,333)
Age group	Total n	Dementia events, n(%)	Incidence rate per 1000PY	Total n	Dementia events, n(%)	Incidence rate per 1000PY
All ages
Overall	112,845	7,547 (6.7%)	10.8/1000PY	14,333	1,090 (7.6%)	9.9/1000PY
Non-initiators	93,941	6,561 (7.0%)	11.4/1000PY	12,540	1,044 (8.3%)	10.6/1000PY
MET Initiators	18,904	986 (5.2%)	8.2/1000PY	1,793	46 (2.6%)	4.0/1000PY
Age 50–64
Overall	65,532	1,608 (2.5%)	3.8/1000PY	8,232	127 (1.5%)	2.0/1000PY
Non-initiators	51,741	1,282 (2.5%)	3.8/1000PY	6,896	114 (1.7%)	2.1/1000PY
MET Initiators	13,791	326 (2.4%)	3.6/1000PY	1,336	13 (1.0%)	1.5/1000PY
Age 65–74
Overall	33,167	3,330 (10.0%)	16.6/1000PY	3,711	406 (10.9%)	13.2/1000PY
Non-initiators	29,114	2,875 (9.9%)	16.4/1000PY	3,360	389 (11.6%)	13.7/1000PY
MET Initiators	4,053	455 (11.2%)	18.1/1000PY	351	17 (4.8%)	7.1/1000PY
Age ≥ 75
Overall	14,146	2,609 (18.4%)	36.3/1000PY	2,390	557 (23.3%)	34.9/1000PY
Non-initiators	13,086	2,404 (18.4%)	36.2/1000PY	2,284	541 (23.7%)	35.2/1000PY
Initiators	1,060	205 (19.3%)	37.3/1000PY	106	16 (15.1%)	26.0/1000PY

VHA = Veterans Health Administration; KPW = Kaiser Permanente Washington; PY=person-years; MET=metformin