Table 1.

Descriptive statistics of the three individual studies.

Statistic	British [2]	Catalan [3]	Swedish [1]
Number of subjects	3245	3501	1603
Cases (%)	1131	875	466
Controls (%)	2114	2626	1137
Age (years)
Minimum	60	7	20
Maximum	103	95	94
Mean	74	58	64
s.d.	7.8	17.1	15.2
Sex
Males (%)	1811 (55.8%)	2405 (68.7%)	851 (53.1%)
Females (%)	1434 (44.2%)	1096 (31.3%)	752 (46.9%)
History of UGI problems
Yes (%)	1307 (40.3%)	1257 (35.9%)	0
No (%)	1841 (56.7%)	2244 (64.1%)	1603 (100%)
Missing (%)	97 (3.0%)	0	0