Table 1.

 Characteristics of cases and controls. Values are numbers (percentages) unless stated otherwise

Characteristics	Cases (n=248)	Controls (n=783)	Standardised difference*
Median (interquartile range) age (years):	82 (75-87)	81 (75-87)	0.01
66-74	66 (27)	203 (26)	0.02
75-84	112 (45)	370 (47)	0.04
≥85	70 (28)	210 (27)	0.03
Female sex	162 (65)	551 (70)	0.11
Median (interquartile range) years of spironolactone use	1 (1-2)	3 (1-5)	0.66
Charlson co-morbidity index:
No hospital admission	37 (15)	214 (27)	0.29
0	13 (5)	94 (12)	0.22
1	41 (17)	131 (17)	0.01
≥2	157 (63)	344 (44)	0.39
History of congestive heart failure (3 years)	132 (53)	282 (36)	0.35
History of chronic liver disease (1 year)	26 (10)	44 (6)	0.19
History of chronic kidney disease (1 year)	13 (5)	17 (2)	0.18
Diabetes	118 (48)	356 (45)	0.04
Residence in a long term care facility	48 (19)	168 (21)	0.05
Median (interquartile range) No of prescription drugs in previous year	17 (14-22)	16 (12-20)	0.34
Drug use in preceding 120 days:
Non-potassium sparing diuretics	201 (81)	561 (72)	0.21
Potassium sparing diuretics†	8 (3)	15 (2)	0.09
β adrenergic receptor blockers	111 (45)	303 (39)	0.12
Potassium supplements	9 (4)	20 (3)	0.06
Non-steroidal anti-inflammatory drugs	90 (36)	202 (26)	0.23
Renin-angiotensin-aldosterone inhibitors	191 (77)	420 (54)	0.49
Fifth of income:
1 (lowest)	49 (20)	171 (22)	0.05
2	64 (26)	167 (21)	0.11
3	53 (21)	140 (18)	0.09
4	41 (17)	159 (20)	0.1
5 (highest)	38 (15)	140 (18)	0.07
Missing	≤5	6 (1)	0.05

*Difference between cases and controls divided by standard deviation; standardised differences <0.1 indicate good balance between cases and controls.

†Amiloride and combination products; triamterene and combination products.