Reduction in laboratory turnaround time decreases emergency room length of stay

Figures & data

Figure 1 Definition of laboratory TAT.

Notes: TAT start time was defined as the latest of lab order/draw time for the first test ordered; end time was defined as the time of completion of the last test ordered within 30 minutes of the first test. Test A-D represent multiple tests used to determine the Lab TAT within the defined time period.
Abbreviations: LOS, length of stay; TAT, turnaround time.

Figure 2 ED LOS correlates with laboratory test TAT.

Notes: (A) Plotting mean and median ED LOS as a function of laboratory test TAT reveals positive correlations with TAT. (B) Box and whisker plot indicates that median LOS increases with each 15 minutes laboratory TAT interval, and that shorter TATs are associated with wider LOS ranges. Horizontal line = median LOS; box = LOS values within upper and lower quartiles; whiskers = LOS range.
Abbreviations: ED, emergency department; LOS, length of stay; TAT, turnaround time.

Table 1 Decrease in LOS as a function of TAT, by patient acuity

Acuity level	Decrease in LOS, in minutes, for each minute of TAT	P-value
1	0.37	<0.0001
2	0.52	<0.0001
3	0.57	<0.0001
4	0.91	<0.0001
Weighted average	0.55

Note: Weighted average was calculated using the numbers of visits by acuity in Table 2.

Abbreviations: LOS, length of stay; TAT, turnaround time.

Table 2 TAT, LOS, estimated LOS reduction and estimated additional admissions by patient acuity level

Acuity level	Visits	Median TAT, hours	Mean LOS,	Median LOS,	Annual LOS reduction, in hours, from a mean TAT reduction of			Annual additional admissions from a mean TAT reduction of
			hours	Hours	5 minutes	10 minutes	15 minutes	5 minutes	10 minutes	15 minutes
1	631	0.9	4.3	4.4	20	39	59	5 (1%)	9 (1%)	14 (2%)
2	2,662	0.9	4.4	4.4	114	229	343	26 (1%)	53 (2%)	80 (3%)
3	7,575	0.9	4.1	4.1	356	713	1,069	87 (1%)	176 (2%)	268 (4%)
4	379	0.7	3.4	3.2	29	57	86	9 (2%)	18 (5%)	27 (7%)
Total	11,247	0.9	4.2	4.1	519	1,038	1,557	127 (1%)	256 (2%)	389 (3%)

Note: Numbers in parentheses are percentages of the number of visits by acuity.

Abbreviations: LOS, length of stay; TAT, turnaround time.

Table S1 Inclusion and exclusion criteria to narrow the cohort for multisite study

Criteria	Hospital visits
ED visits	4,483,169
ED visits from hospitals reporting laboratories to Cerner	4,027,564
ED visits with at least one laboratory test	1,096,724
LOS ≥0 minutes	1,096,167
Age ≥ 18 years	945,342
Assigned gender (male or female only)	944,668
Exclude patients with all cancelled tests	944,668
Laboratory drawn and complete date-times are populated	944,668
Laboratory is drawn within LOS	922,546
LOS <7 hours	642,322
“Treat-and-release” discharge dispositions	515,473
Exclude patients where laboratory results came after discharge	483,429
Exclude patients with TAT ≤5 minutes	463,712

Abbreviations: ED, emergency department; LOS, length of stay; TAT, turnaround time.

Table S2 Inclusion and exclusion criteria to narrow the cohort for single-site study

Criteria	Hospital visits
Data as delivered	52,080
Age ≥ 18 years	51,892
With at least one blood-based laboratory	30,817
Assigned gender (male or female only)	30,817
“Treat-and-release”, that is, patient departed hospital	16,425
Non-missing principal complaint	16,421
LOS <7 hours	11,247
Available visits	11,247

Abbreviation: LOS, length of stay.

Table S3 Patient demographics and distribution by acuity for the single-site study

Patient demographics	Acuity level	1	2	3	4	Total
	n	631	2,662	7,575	379	11,247
Chief complaint	Other pain loci	3.0	6.8	14.1	23.5	12.1
(top 10), %	Abdominal pain	2.2	5.4	15.3	0.8	11.8
	Nausea/vomiting/diarrhea	3.0	3.6	10.2	0.8	7.9
	Chest pain	2.4	13.2	4.8	0.3	6.5
	Headache	5.7	5.1	4.8	2.4	4.8
	Back pain	2.9	2.3	4.5	16.1	4.3
	Dizziness	7.0	4.5	3.0	0.8	3.5
	Status post–fall	3.0	5.4	2.9	3.2	3.5
	Dyspnea	4.4	6.2	2.3	0.0	3.3
	Fever	1.9	3.0	3.0	0.5	2.8
Gender, %	Female	54.7	57.1	65.3	71.5	63.0
	Male	45.3	42.9	34.7	28.5	37.0
Age, years, %	18–19	4.0	3.9	4.0	3.7	4.0
	20–29	21.9	16.6	23.2	28.5	21.7
	30–39	17.6	14.4	17.3	20.8	16.7
	40–49	12.4	14.2	15.2	13.7	14.8
	50–59	17.9	17.9	16.1	14.0	16.6
	60–64	8.2	8.0	6.5	4.7	6.9
	≥65	18.1	25.1	17.7	14.5	19.4
Arrival day, %	Monday-Friday	74.5	76.7	71.0	69.7	72.5
	Weekend	25.5	23.3	29.0	30.3	27.5
Arrival time, %	Day shift (9 am-5 pm)	47.5	46.0	44.9	45.4	45.3
	Night shift	52.5	54.0	55.1	54.6	54.7
Mode of arrival, %	Ambulance	43.9	33.3	19.3	10.6	23.7
	Non-ambulance	56.1	66.7	80.7	89.4	76.3
Discharge diagnosis	Signs/symptoms	10.1	14.8	25.3	5.5	21.3
category (top 10), %	Nervous system and sense	28.2	14.4	10.0	5.8	11.9
	Circulatory	13.5	17.5	7.8	3.2	10.3
	Genitourinary	2.1	5.3	10.8	16.6	9.2
	Injury/poisoning	16.3	9.2	7.1	17.7	8.5
	Respiratory	7.3	8.0	8.8	5.8	8.4
	Musculoskeletal/connective tissue	6.7	4.9	8.6	25.6	8.2
	Digestive	1.0	4.8	7.3	1.6	6.2
	Mental illness	3.5	8.0	2.5	0.8	3.8
	Pregnancy/childbirth/puerperium	1.7	2.7	3.2	1.6	2.9