Table 2.

Concurrent validity of indicators of prescribing quality based on cut-offs of number of drugs in the medication list (polypharmacy indicators)

Number of drugs (cut-off for indicator)	Patients identified by the indicator n	According to gold standard			Sensitivity (95 % CI)	Specificity (95 % CI)
		Suboptimal drug treatment		Appropriate drug treatment
		Confirmed n (PPV)	Not identified n (%)	Identified n (NPV)
≥1	192	141 (0.73)	0 (0)	8 (1.00)	1.00 (0.97; 1.00)	0.14 (0.07; 0.23)
≥2	189	141 (0.75)	0 (0)	11 (1.00)	1.00 (0.97; 1.00)	0.19 (0.10; 0.29)
≥3	176	136 (0.77)	5 (3.5)	19 (0.79)	0.96 (0.93; 0.99)	0.32 (0.22; 0.45)
≥4	163	129 (0.79)	12 (8.5)	25 (0.68)	0.91 (0.86; 0.95)	0.42 (0.30; 0.54)
≥5	149	121 (0.81)	20 (14)	31 (0.61)	0.86 (0.80; 0.92)	0.53 (0.41; 0.65)
≥6	137	111 (0.81)	30 (21)	33 (0.52)	0.79 (0.72; 0.86)	0.56 (0.44; 0.68)
≥7	114	96 (0.84)	45 (32)	41 (0.48)	0.68 (0.61; 0.76)	0.69 (0.57; 0.79)
≥8	84	71 (0.85)	70 (50)	46 (0.40)	0.50 (0.42; 0.60)	0.78 (0.66; 0.86)
≥9	71	61 (0.86)	80 (57)	49 (0.38)	0.43 (0.35; 0.52)	0.83 (0.71; 0.90)
≥10	49	45 (0.92)	96 (68)	55 (0.36)	0.32 (0.25; 0.40)	0.93 (0.82; 0.97)

CI confidence interval, NPV negative predictive value, PPV positive predictive value