Warfarin monitoring in nursing homes assessed by case histories. Do recommendations and electronic alerts affect judgements?

Figures & data

Figure 1. Case histories and questionnaire.

Table 1. Definition and number (%) of acceptable and unacceptable answers in case history A and B.

	n	%	n	%
Case history A
Answered all questions in case A	378	100
Acceptable answers
Unchanged dose (50 mg) and INR within 3 weeks	231	61
Unacceptable answers	147	39	147	100
Changed dose and/or inadequate INR recall interval
Changed dose			55	37
Unchanged dose, but inadequate INR recall interval			92	63
Total	378	100	147	100
Case history B
Answered all questions in case B	365	100
Acceptable answers
Dose reduction from 25 mg to 15–20 mg and INR in 2–4 days	33	9
Unacceptable answers	332	91	332	100
Unacceptable dose and/or inadequate INR recall interval
Dose of warfarin not in the 15–20 mg range			258	78
15–20 mg warfarin, but inadequate INR recall interval			74	22
Total	365	100	332	100

INR: Prothrombin Time International Normalized Ratio.

Table 2. Characteristics of the responding physicians and nursing home settings.

Characteristics	Results
Total number of physicians, n	378^a
	n	%
Gender
Female	148	44
Male	185	56
Age
25–35 years	103	31
36–50 years	113	34
>50 years	114	35
Main employment
Nursing home physician	122	37
General practitioner	178	54
Other	28	9
Time employed as a nursing home physician
≤3 years	152	46
>3 years	177	54
Type of employment in the nursing home
Part-time (<20%)	63	19
Part-time (20–49%)	143	44
Part-time (≥50%) or full-time	119	37
INR instrument available in the nursing home
No	184	55
Yes	153	45
Specialist status
Specialist	161	51
Non-specialist	158	49

INR: Prothrombin Time International Normalized Ratio.

^a 42 (11%)–60 (16%) of the responders did not answer one or more questions about person and practice particulars.

Table 3. Warfarin doses and INR recall intervals given by the physicians in case history A and B.

	Warfarin dose (mg)Median (10–90 percentile)	Recall interval (days)Median (10–90 percentile)
Case history A (n = 378)
Acceptable answers; n = 231 (61%)	50 (50–50)	14 (7–21)
Unacceptable answers; n = 147 (39%)	50 (46.7–50)^a	28 (7–28)^a
Case history B (n = 365)
Before reading the electronic alert (n = 365)
Acceptable answers; n = 33 (9%)	17.5 (17.5–20)	3 (2–4)
Unacceptable answers; n = 332 (91%; 74 respondents with correct dose reduction only, of whom 58 chose not to change their answers after the alert)	25 (17.5–25)^a	7 (3–14)^a
Changes in the unacceptable answers in response to the electronic alert (n = 162)
Now acceptable; n = 47 (29%; all with correct dose reduction)
Answer before the alert	25 (17.5–25)	4 (2–7)
Answer after the alert	17.5 (17.5–20)	3 (3–4)
Still unacceptable; n = 115 (71%; 54 with correct dose reduction)^b
Answer before the alert	25 (22.5–25)	7 (3–21)
Answer after the alert	20 (15–25)	7 (3–8)

INR: Prothrombin Time International Normalized Ratio.

^a Statistical significant difference (p < .05).

^b Overall, the number of respondents with correct dose reduction in case B increased from 33 + 74 = 107 (29%) before the alert to 33 + 58 + 47 + 54 = 192 (53%) after reading the alert.