Table 2.

Association between geriatric conditions and other subject characteristics and adverse drug events

Predictor	Bivariate IRR (95% CI)	P Value	Multivariable IRR (95% CI)	P Value
Patient age	0.99 (0.96 – 1.02)	0.54	0.99 (0.96 – 1.02)	0.43
Male sex	1.11 (0.41 – 3.00)	0.84	†
Non-white race	0.75 (0.19 – 3.03)	0.69	†
Number of medications at baseline	1.03 (0.99 – 1.06)	0.09	1.03 (0.99 – 1.08)	0.16
High-risk medications used at baseline
Glucose-lowering drug	0.65 (0.44 – 0.95)	0.03	0.61 (0.41 – 0.91)	0.02
Loop diuretic	1.25 (0.91 – 1.73)	0.17	1.20 (0.81 – 1.78)	0.37
Digoxin	1.10 (0.66 – 1.85)	0.71	1.06 (0.59 – 1.89)	0.86
Anticonvulsant	0.88 (0.50 – 1.55)	0.66	0.79 (0.44 – 1.43)	0.44
Any Beers criteria drug	0.96 (0.54 – 1.74)	0.91	0.95 (0.51 – 1.76)	0.86
Warfarin	0.87 (0.41 – 1.86)	0.72	†
Benzodiazepine	0.70 (0.31 – 1.59)	0.40	†
Number of high-risk medications at baseline ‡	0.94 (0.79 – 1.11)	0.45	0.84 (0.69 – 1.03) *	0.10
Self-reported health score ≥ 75	1.12 (0.81 – 1.54)	0.49	1.21 (0.86 – 1.70)	0.28
IADL dependencies (Ref: Fully independent)
Mild dependence	1.18 (0.81 – 1.72)	0.80	1.25 (0.84 – 1.86)	0.95
Moderate or severe dependence	0.98 (0.61 – 1.56)		0.91 (0.54 – 1.54)
Geriatric conditions
Cognitive impairment	1.11 (0.73 – 1.68)	0.63	1.12 (0.72 – 1.72)	0.62
Depression	1.10 (0.73 – 1.68)	0.65	0.95 (0.60 – 1.49)	0.82
Visual impairment	0.69 (0.41 – 1.18)	0.18	0.69 (0.39 – 1.21)	0.19
Incontinence	1.18 (0.70 – 2.01)	0.53	1.01 (0.57 – 1.77)	0.98
Constipation	0.88 (0.45 – 1.72)	0.70	0.77 (0.38 – 1.55)	0.47
Fall or gait instability	1.91 (0.78 – 4.65)	0.15	1.91 (0.71 – 5.14)	0.20
Geriatric burden score* (Ref: 0)
1	0.95 (0.68 – 1.33)	0.81	0.84 (0.58 – 1.21) *	0.79
2 or more	1.13 (0.70 – 1.81)		1.04 (0.63 – 1.73) *
Other comorbid conditions
Congestive heart failure	1.26 (0.77 – 2.09)	0.36	0.97 (0.50 – 1.87)	0.93
Chronic renal insufficiency	0.83 (0.46 – 1.50)	0.55	0.76 (0.41 – 1.40)	0.37
Number of comorbidities (Ref: < 10)
10 – 13 comorbidities	1.14 (0.79 – 1.66)	0.37	1.17 (0.78 – 1.76)	0.57
≥ 14 comorbidities	1.18 (0.82 – 1.71)		1.14 (0.71 – 1.84)
Study group (intervention vs. control)	0.94 (0.70 – 1.28)	0.70	0.89 (0.64 – 1.23)	0.47

^*Geriatric burden score is collinear with IADL dependencies and the geriatric conditions listed in the table, and the number of high-risk medications is collinear with the specific high-risk medications listed in the table. The multivariable parameter estimates for these summative variables are derived from separate models that excluded the collinear covariates. Results are combined into a single table for clarity of presentation.

^†Male sex, non-white race, and use of warfarin and benzodiazepines were not included in the multivariable model to preserve statistical power for the remaining covariates (see methods).

^‡Not counting Beers criteria drugs (to prevent double-counting, since certain benzodiazepines and higher-dose digoxin prescriptions are counted as Beers criteria drugs).