Baseline characteristics for patients with serum potassium values obtained at presentation to the emergency department and at hospital admission
| At emergency department | At hospital admission | |||
|---|---|---|---|---|
| N=64 579 | N=64 497 | |||
| Demographics | ||||
| Age (years) median (IQR) | 77 (71–83) | 77 (71–83) | ||
| Women (n (%)) | 35630 (55.2) | 32965 (51.1) | ||
| Income quintile (n (%)) | ||||
| One (lowest) | 14231 (22.0) | 13900 (21.6) | ||
| Two | 12921 (20.0) | 12928 (20.0) | ||
| Three (middle) | 12542 (19.4) | 12792 (19.8) | ||
| Four | 11496 (17.8) | 11601 (18.0) | ||
| Five (highest) | 12407 (19.2) | 12446 (19.3) | ||
| Rural Location (n (%)) | 11438 (17.7) | 13248 (20.5) | ||
| Year of cohort entry (n (%)) | ||||
| 2003–2004 | 6586 (10.2) | 11601 (18.0) | ||
| 2005–2006 | 15188 (23.5) | 15640 (24.3) | ||
| 2007–2008 | 20569 (31.9) | 18474 (28.6) | ||
| 2009–2010 | 22236 (34.4) | 18782 (29.1) | ||
| Long-term care facility utilisation (n (%)) | 4137 (6.4) | 3681 (5.7) | ||
| comorbidities, (n (%)) | ||||
| Chronic kidney disease† | 5335 (8.3) | 6427 (10.0) | ||
| Diabetes mellitus‡ | 13142 (20.4) | 13632 (21.1) | ||
| Peripheral vascular disease | 1690 (2.6) | 2937 (4.6) | ||
| Coronary artery disease§ | 26979 (41.8) | 30528 (47.3) | ||
| Heart failure | 13691 (21.2) | 15173 (23.5) | ||
| Stroke/Transient ischemic attack | 2455 (3.8) | 2655 (4.1) | ||
| Chronic liver disease | 1238 (1.9) | 1645 (2.6) | ||
| Medication use in prior 6 months, n (%) | ||||
| ACE inhibitors | 22690 (35.1) | 23770 (36.9) | ||
| Angiotensin-receptor blockers | 10442 (16.2) | 10012 (15.5) | ||
| Potassium sparing diuretics | 5657 (8.8) | 6147 (9.5) | ||
| Loop diuretics | 13553 (21.0) | 14618 (22.7) | ||
| Thiazide diuretics | 12334 (19.1) | 12458 (19.3) | ||
| Calcium channel blockers | 19126 (29.6) | 19951 (30.9) | ||
| β-adrenergic antagonists | 21989 (34.1) | 23382 (36.3) | ||
| Statins | 24892 (38.6) | 25273 (39.2) | ||
| NSAIDS (excluding aspirin) | 11621 (18.0) | 12573 (19.5) | ||
| Anticonvulstants | 3847 (6.0) | 3740 (5.8) | ||
| Antidepressants | 15662 (24.3) | 15075 (23.4) | ||
| Antipsychotics | 4001 (6.2) | 3532 (5.5) | ||
| Benzodiazepine | 15295 (23.7) | 15515 (24.1) | ||
| Antineoplastic drugs | 3285 (5.1) | 3624 (5.6) | ||
| Baseline laboratory measurements¶ | ||||
| Serum creatinine levels | ||||
| Most recent serum creatinine (µmol/l) median (IQR) | 90 (74–114) | 90 (74–114) | ||
| GFRŦ levels | ||||
| Most recent eGFR (ml/min/1.73 m2), median (IQR) | 63 (47–79) | 63 (47–79) | ||
| eGFR category (n (%))(ml/min/1.73 m2) | ||||
| ≥60 | 20807 (54.7) | 23842 (55.3) | ||
| 45–59 | 8527 (22.4) | 9566 (22.2) | ||
| 30–44 | 5466 (14.4) | 5989 (13.9) | ||
| 15–29 | 2362 (6.2) | 2694 (6.2) | ||
| <15 | 850 (2.2) | 1021 (2.4) | ||
| Serum sodium levels | ||||
| Most recent serum sodium (mmol/l) median (IQR) | 139 (137–141) | 139 (137–141) | ||
| Serum potassium levels | ||||
| Most recent serum potassium (mmol/l) median (IQR) | 4.2 (3.8–4.5) | 4.1(3.8–4.5) | ||
*We defined index date as the time of cohort entry.
†Assessed by administrative database codes: CIHI ICD-9 codes—4030, 3031, 4039, 4040, 4041, 4049, 582, 583, 580, 581, 584, 585, 586, 587, 5880, 5888, 5889, 5937; CIHI ICD-10 codes—I12, I13, N01, N03, N05, N07, N14, N15, N00, N04, N08, N18, N19, N26, N25, N137, N280, N2888, N06, N391; OHIP diagnostic codes—403, 580, 581, 585.
‡Assessed by diabetic medication use in previous 6 months.
§Coronary artery disease includes receipt of coronary artery bypass graft surgery, percutaneous coronary intervention and diagnoses of angina.
¶Available from emergency department, inpatient or outpatient settings for a subpopulation. A total of 33 104 (51.3%), 32 844 (50.9%) and 38 012 (58.9%) patients at presentation to emergency department had a baseline serum potassium, sodium and creatine measurement available in the 7–365 days prior to the index date, respectively. Among these patients, the baseline measurements were taken at a median (IQR) of 75 (25–174), 75(25–174) and 76 (26–173) days, respectively. A total of 39 552 (61.3%), 39 422 (61.1%) and 43 112 (66.9%) patients at hospital admission had a baseline serum potassium, sodium and creatine measurement available in the 7–365 days prior to the index date, respectively. Among these patients, the baseline measurements were taken at a median (IQR) of 29 (14–97), 29 (14–97) and 32(14–101) days, respectively.
ŦeGFR was calculated using the CKD-Epi equation.
CKD-Epi equation:141×min((serum creatine in µmol/l/88.4)/κ, 1)α × max((serum creatine in µmol/l/88.4)/κ, 1)−1·209×0.993Age × 1.018 (if female)×1.159 (if African American) κ=0.7 for females and 0.9 for males, α=−0.329 for females and −0.411 for males, min=the minimum of Scr/κ or 1, max=the maximum of Scr/κ or 1. Racial information was not available in our data sources and all patients were assumed not to be of non African-Canadian race. This was a reasonable assumption; as of 2006, African-Canadians represented less than 7% of the Ontario population. Source: http://www12.statcan.ca/census-recensement/2006/dp-pd/hlt/97–562/index.cfm?Lang=E
eGFR, estimated glomerular filtration rate.