Table 4.

Lung function studies

Study	Time	Cross-sectional (C)/Longitudinal (L)	Age range	N	Age ≥65 years	Decline
Morris et al	1969–70	C	20–84	988	79	Linear
Crapo et al	1979–80	C	18–91	251	68	Linear
Knudson et al	1972–75	C	6–88	421	-	Linear
Dockery et al	1974–76	C	25–74	2454	430	Nonlinear
Burrows et al	1972–84	L	20–72	466	-	Nonlinear
Ware et al	1974–83	L	25–74	2454	430	Nonlinear
Enright et al	1989–90	C	65–85	777	777	Linear

Note: Adapted from Kerstjens HAM, Rijcken B, Schouten JP, et al. 1997. Decline of FEV by age and smoking status: facts, figures, and fallacies. Thorax, 52:820-7. Copyright © 1997. Reproduced with permission from BMJ.