Table 1

Completeness of BMI data in the CPRD, by age and calendar period

Age group (years)	1990–1994	1995–1999	2000–2004	2005–2011
16–24*
N registered	11 423	17 501	34 452	42 546
BMI in the previous 3 years (%)	26	28	25	32
BMI in the previous (%)	26	37	30	37
25–34
N registered	17 477	29 923	48 659	50 413
BMI in the previous 3 years (%)	37	39	36	49
BMI in the previous (%)	38	66	67	72
35–44
N registered	15 953	28 838	55 991	61 014
BMI in the previous 3 years (%)	36	36	31	46
BMI in the previous (%)	39	67	71	80
45–54
N registered	14 507	27 765	48 093	55 564
BMI in the previous 3 years (%)	39	37	32	50
BMI in the previous (%)	42	70	73	84
55–64
N registered	11 680	20 843	42 258	49 380
BMI in the previous 3 years (%)	42	40	37	57
BMI in the previous (%)	44	74	77	87
65–74
N registered	10 678	17 605	30 997	34 508
BMI in the previous 3 years (%)	36	37	40	67
BMI in the previous (%)	38	71	79	91
75+
N registered	8637	16 005	29 384	32 523
BMI in the previous 3 years (%)	28	32	37	64
BMI in the previous (%)	28	56	69	87
Total
N registered	90 355	158 480	289 834	325 948
BMI in the previous 3 years (%)	35	36	34	51
BMI in the previous (%)	37	64	67	77

N registered is all those under follow-up at the midpoint of the period.
*BMI measurements from age <16 years were not counted in this analysis; hence, completeness in the 16–24 age group may be artificially low.