Keywords
head - neck - surgery - complications
Introduction
Head and neck surgery remains a complex field; patients with these kinds of pathologies can suffer significant functional or life-threating complications after treatment that need unplanned readmissions increasing the cost related to the treatment. In 2014, the United States Healthcare system spent US$3 trillion and, to try to decrease this, a hospital readmissions reduction program was applied to evaluate the quality of care and the financial implications[1].
The causes of 30-day readmission for surgical patients differ from those of medical patients; nonetheless, readmissions after surgical procedures can also be secondary to a medical condition or to complications or comorbidity exacerbated by the procedure itself.[2]
[3]
[4]
Prior studies performed in North American otorhinolaryngology - head and neck surgery departments seeking to identify risk factors for unplanned hospital readmission among patients undergoing otolaryngology procedures reported rates of hospital readmission ranging from 3.1 to 7.3%.[2]
[4]
[5]
[6]
[7]
[8]
[9] These studies identified a strong association between the occurrence of postoperative complications and unplanned 30-day readmissions.[2]
[10] In another study that included 1,058 patients undergoing ear, nose, and throat (ENT) surgery, Graboyes et al. found that patients who experienced a complication during or after their index hospitalization were 11.9 times more likely to be readmitted to the hospital within 30 days than patients without complications.[2] Regarding the reported 30-day readmission rates for head and neck surgery, it ranges from 3.2 to 26.5%, depending on the subsite, on the complexity of the surgery, and on a variety of factors.[2]
[3]
[7]
[8]
[9]
[11]
[12]
There is no data reported from European otorhinolaryngology - head and neck surgery departments about unplanned hospital readmission after head and neck surgery. Moreover, further understanding is needed about the risk factors associated with this. For that reason, the objective of the present study was to evaluate prospectively the incidence risk factors and causes associated with 30-day unplanned hospital readmission and visit to the emergency room (ER) after surgery for head and neck tumors.
Materials and Methods
A prospective, longitudinal, nonrandomized study was performed with the approval of the Ethics Committee of our Center (CCH-071719). Patients diagnosed with benign or malignant head and neck pathology, ≥ 18 years old, undergoing inpatient or outpatient head and neck surgery in a tertiary university hospital between July of 2016 and July 2019 were included consecutively, excluding patients undergoing thyroid surgery (which is performed by general surgeons at our institution). Unplanned readmission was defined as “any unplanned readmission to the same or another hospital for a postoperative occurrence likely related to the principal surgical procedure within 30 days of the procedure”.[9] Thus, hospital readmissions that occurred within 30 days of surgery and were planned or unrelated to the first surgical procedure were excluded. To achieve this, a follow-up protocol was conducted during the first 30 days after patient discharge to identify and classify any additional episodes of a visit to the emergency room or the need of readmission.
The demographic data (age, sex), comorbidities, diagnosis, stage in case of malignancy, imaging (computed tomography [CT], magnetic resonance imaging [MRI], ultrasound), the American Society of Anesthesiologists (ASA) classification, type of surgery, complications, outcomes after surgery, among others, were obtained during data collection. Readmission and the emergency room visit analysis was performed on this data.
Statistical analysis was performed with IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY, USA). Quantitative variables are expressed as media ± standard deviation (SD). Bivariate analysis using chi-squared and t-tests were used to analyze categorical and continuous variables, respectively. Univariate and multivariate logistic regression analysis was used to identify factors associated with 30-day readmission. Odds ratios (OR) and 95% confidence intervals (95%CIs) were calculated for the strength of association. All tests were 2-sided, and a p-value < 0.05 was considered statistically significant.
Results
A total of 834 patients, which represent 13.6% of the annual volume of patients of our department (2,096 surgeries per year and 6,288 surgeries in 3 years) met the inclusion criteria, 726 in the group of major surgery and 108 in the group of minor surgery. Of these, 573 (68.7%) were male and 261 (31.3%) were female. The age average was 59 years old (SD = 14.80; minimum 18; maximum 90). All demographic data are presented in [Table 1]. The patients had undergone a primary surgery of the head and neck region due to benign or malignant tumors, with a 30-day readmission rate for all causes of 7.9% for patients treated by a major surgery and of 0% for patients treated in the outpatient clinic for minor procedures, to a total rate of readmission of 6.8%. The rate of a visit to the emergency room for all causes in the first 30 days was of 14% for patients treated by major surgery and of 2.7% for patients treated in the outpatient clinic ([Table 2]).
Table 1
Demographic data and univariant analysis comparing parameters between patients who needed to be readmitted or visited the emergency room in the first 30 days after hospital discharge
|
n
|
%
|
Patients not readmitted
|
Patients readmitted
|
30-day readmission
p-value
|
Patients who did not visit the ER
|
Patients who needed to visit the ER
|
30-day visit to the ER
p-value
|
|
Number of patients
|
834
|
|
|
|
|
|
|
|
|
Age
|
59 years old ± 14.80 (Min. 18/Max. 90)
|
|
|
|
|
|
|
|
|
Sex
Male
Female
|
573
261
|
68.7
31.3
|
531
246
|
42
15
|
0.682
|
492
231
|
81
30
|
0,546
|
|
Type of surgery
- Major Surgery
- Minor Surgery (Outpatient Clinic)
|
726
108
|
87
13
|
669
108
|
57
0
|
0.001
|
621
105
|
105
3
|
0.001
|
|
Smoking
Yes
No
N° Packs per year
|
435
399
25.37 ± 26.1 (Min: 8/Max: 100)
|
52.1
47.9
|
393
384
|
42
15
|
0.728
|
360
363
|
75
36
|
0.498
|
|
Alcohol (> 70 gr/day)
Yes
No
|
303
531
|
36.3
63.7
|
276
501
|
27
30
|
0.721
|
258
465
|
45
66
|
0.074
|
|
HTA
Yes
No
|
327
507
|
35.6
64.4
|
300
477
|
27
30
|
0.950
|
273
450
|
54
57
|
0.663
|
|
DM
Yes
No
|
117
717
|
14
86
|
102
669
|
15
42
|
0.162
|
99
618
|
18
99
|
0.141
|
|
Malnutrition (BMI < 18.5)
|
39
|
4.67
|
27
|
12
|
0.070
|
21
|
18
|
0.248
|
|
Obesity
|
183
|
21.9
|
165
|
18
|
0.082
|
156
|
27
|
0.043
|
|
COPD
|
87
|
10.4
|
81
|
6
|
0.770
|
78
|
9
|
0.279
|
|
Cardiopathy
|
144
|
17.2
|
129
|
15
|
0.966
|
117
|
27
|
0.354
|
|
ASA
I
II
III
IV
|
60
444
213
3
|
8.3
61.2
29.3
0.4
|
54
417
189
3
|
6
27
24
0
|
0.006
|
48
384
180
3
|
12
60
33
0
|
0.002
|
|
Neoadjuvant treatment (RT/CRT)
|
56/726
|
7.7
|
53
|
3
|
0.256
|
52
|
4
|
0.301
|
|
Flap:
|
63/726
|
8.6
|
54
|
9
|
0.232
|
45
|
18
|
0.151
|
|
Length of stay
|
6.43 ± 9.2 (Min: 1/Max: 74)
|
|
|
|
|
|
|
|
|
Length of stay > 7 days
|
150/726
|
20.7
|
129
|
21
|
0.123
|
108
|
42
|
0.204
|
|
Wound class
- Clean
- Clean/contaminated
- Contaminated
|
366
138
330
|
43.8
16.5
39.6
|
339
117
321
|
27
21
9
|
0.002
|
315
105
303
|
51
33
27
|
0.001
|
|
Type of histology (*)
Benign
Malignant
|
384
342
|
52.89
47.11
|
366
303
|
18
39
|
0.054
|
342
279
|
42
63
|
0.130
|
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; CRT, chemoradiotherapy; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; ER, emergency room; HTA, arterial hypertension; RT, radiotherapy.
(*) Major Surgery.
Table 2
Multivariant analysis of variables associated with readmission or visit to the emergency room
|
30-day Readmission
|
30-day visit to the ER
|
|
Age
|
0.430 (95%CI: - 0.651–1.579)
|
0.218 (95%CI: - 0.651–1.579)
|
|
Sex
Male
Female
|
0.858 (95%CI: - 0.308–- 0.181)
|
0.639 (95%CI: - 0.249–- 0.111)
|
|
Type of surgery
- Major Surgery
- Minor Surgery (Outpatient Clin95%CI)
|
0.001 (95%CI: - 0.784–- 0.677)
|
0.001 (95%CI: - 0.724–- 0.607)
|
|
Smoking
N° Packs per year
|
0.181 (95%CI: - 0.455–- 0.301)
|
0.385(95%CI: - 0.496–- 0.193)
|
|
Alcohol (> 70 gr–day)
|
0.463 (95%CI: - 0.358–- 0.232)
|
0.187 (95%CI: - 0.405–0.801)
|
|
HTA
|
0.483 (95%CI: - 0.388–- 0.260)
|
0.537 (95%CI: - 0.323–0.169)
|
|
DM
|
0.676 (95%CI: - 0.147–0.154)
|
0.663 (95%CI: - 0.084–0.221)
|
|
Malnutrition (BMI < 18.5)
|
0.009 (95%CI: - 0.015–0.065)
|
0.021 (95%CI: - 0.323–- 0.270)
|
|
Obesity
|
0.720 (95%CI: - 0.237–- 0.110)
|
0.980(95%CI: - 0.178–- 0.037)
|
|
COPD
|
0.585 (95%CI: - 0.091–0.005)
|
0.353 (95%CI: - 0.034–- 0.077)
|
|
Chronic cardiac disease
|
0.550 (95%CI: -0.156–- 0.052)
|
0.776 (95%CI: - 0.097–0.018)
|
|
ASA
I
II
III
IV
|
0.001 (95%CI: 0.216–0.384)
|
0.008 (95%CI: 0.280–0.454)
|
|
Flap:
|
0.571 (95%CI: 0.340–0.769)
|
0.613 (95%CI: - 0.707–- 0.270)
|
|
Neoadjuvant treatment (RT–CRT)
|
0.345 (95%CI: 0.179–0.467)
|
0.412 (95%CI: 0.123–0.671)
|
|
Length of stay >7 days
|
0.067 (95%CI: 0.776–0.851)
|
0.055 (95%CI: 0.840–0.919)
|
|
Wound class
- Clean
- Clean/contaminated
- Contaminated
|
0.008 (95%CI: 0.071–0.237)
|
0.006 (95%CI: - 0.022–0.202)
|
|
Type of histology
Benign
Malignant
|
0.083 (95%CI: - 0.255–- 0.111)
|
0.184(95%CI: - 0.392–- 0.083)
|
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; CRT, chemoradiotherapy; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; ER, emergency room; HTA, arterial hypertension; RT, radiotherapy.
In the group of major surgery, 42 (10.9%) patients treated for benign tumors and 63 (18.4%) patients treated for malignant tumors presented to the emergency room in the first 30 days after discharge (p = 0.130). Moreover, 18 (4,6%) patients treated for benign tumors and 39 (11,4%) treated for malignant tumors needed to be readmitted at the hospital to treat some complication in first 30 days after discharge (p = 0.054). The most common subsites were the larynx (n = 271), followed by parotid gland surgery (n = 127), skin cancer (n = 44), oral tongue (n = 32), and the oropharynx (n = 31).
In our patient population, 7.9% had unplanned hospital readmission, and 14.5% needed to visit the emergency room. When we evaluated the variables in the univariate and multivariate analysis, we only found statistical significance related to need the rate of readmission or visit to the emergency room according to the type of surgery (major versus minor procedures), ASA classification, or wound class. However, when we compared the results between the patients in the major surgery group who needed to be readmitted or who needed to visit the emergency room in the first 30 days after discharge and those who did not need, malignant histology (p = 0.006), ASA (p = 0.001), malnutrition (p = 0.002), and length of hospitalization > 7 days (p = 0.016) were related to a major risk of readmission, while ASA (p = 0.001), malnutrition (p = 0.002) and length of hospitalization > 7 days (p = 0.016) were related to a major risk of visit to the emergency room in the first 30 days after discharge ([Table 3]). In contrast, other factors, such as the need of neoadjuvant treatment with radiotherapy or chemoradiotherapy, were not related with an increased risk of readmission (p = 0.256) or with visit to the emergency room (p = 0.301). Data about the type of major surgery performed, the cause of a visit to the emergency room, the most common cause of readmission or reintervention, and the type of reintervention can be seen on [Tables 4], [5], [supplementary Table S1], [S2] and [supplementary Fig S1] (online only).
Table 3
Comparisons of factors between patients who needed to be readmitted or visited the emergency room in the major surgery group
|
Variable
|
Need of readmission (p)
|
Need of visit to the ER (p)
|
|
Gender
|
0.113
|
0.679
|
|
Smoking
|
0.195
|
0.234
|
|
Alcohol
|
0.427
|
0.618
|
|
Histology: malignant
versus
benign
|
0.006
|
0.195
|
|
ASA
|
0.001
|
0.001
|
|
Malnutrition (BMI < 18.5)
|
0.002
|
0.001
|
|
Obesity
|
0.516
|
0.790
|
|
DM
|
0.513
|
0.856
|
|
HTA
|
0.391
|
0.278
|
|
COPD
|
0.729
|
0.361
|
|
Cardiopathy
|
0.401
|
0.643
|
|
Neoadjuvant treatment RT/CRT
|
0.163
|
0.413
|
|
Length of hospitalization > 7 days
|
0.016
|
0.002
|
Abbreviations: CRT, chemoradiotherapy; DM, diabetes mellitus; HTA, arterial hypertension; COPD, chronic obstructive pulmonary disease; RT, Radiotherapy.
Table 4
Cases according to major or minor Surgery, 30-day readmission rate, 30-Day visit to the emergency room, type of histology, hospital readmission length of stay, and need of reintervention
|
Variables
|
n
|
%
|
|
Major surgery
|
726
|
87
|
|
30-day readmission rate
|
57
|
7.9
|
|
30-day visit to the ER
|
102
|
14
|
|
Minor surgery
|
108
|
13
|
|
30-day readmission rate
|
0
|
0
|
|
30-day visit to the ER
|
3
|
2.7
|
|
Visit to the ER according to histology
|
|
|
|
Benign
|
42/384
|
10.9
|
|
Malignant
|
60/342
|
17.5
|
|
Readmission according to histology
|
|
|
|
Benign
|
18/384
|
4.6
|
|
Malignant
|
39/342
|
11.4
|
|
Hospital readmission length of stay
|
2 ± 1.6
(Min: 1/Max: 17)
|
|
|
Need of reintervention by cause
|
|
|
|
Infection/abscess
|
11
|
|
|
Fistula
|
4
|
|
|
Intestinal perforation
|
3
|
|
|
Wound/skin dehiscence
|
3
|
|
|
Haemoptysis/oral bleeding
|
3
|
|
|
Total
|
24
|
2.8%
|
|
Cause
|
Procedure
|
|
|
Infection/abscess
|
Surgical drainage in all cases
|
|
Fistula
|
Pectoralis major flap in 3 cases, supraclavicular flap in 1 case.
|
|
Intestinal perforation
|
Surgical revision by general surgeons.
|
|
Wound/skin dehiscence
|
Skin suture in all cases.
|
|
Haemoptysis/oral bleeding
|
Surgical revision and hemostasis.
|
Table 5
Types of surgery performed and the rate of visit to the ER or of readmission in the first 30 days
|
Major Surgery
|
Visit to the ER
|
Need of Readmision
|
Minor Surgery
|
Visit to the ER
|
Need of Readmision
|
|
Laser surgery of the larynx without neck dissection
|
12/184
|
6/184
|
Adenectomy
|
2/36
|
0/36
|
|
Laser surgery of the supraglottis with neck dissection
|
12/38
|
9/38
|
Tracheostomy closure
|
0/15
|
0/15
|
|
Laser surgery of the hypopharynx
|
6/25
|
6/25
|
Sebaceous cyst resection
|
0/12
|
0/12
|
|
Cricopharyngeal laser miotomy
|
0/1
|
0/1
|
Oral leucoplakia biopsy
|
0/12
|
0/12
|
|
Total laryngectomy
|
10/49
|
5/49
|
Oral papilloma resection
|
0/12
|
0/12
|
|
Oropharyngectomy
|
6/31
|
3/31
|
Facial palsy outpatient surgery
|
1/9
|
0/9
|
|
Oral tongue cancer
|
2/32
|
1/32
|
Oral angioma resection
|
0/6
|
0/6
|
|
Lip cancer resection
|
1/14
|
0/14
|
Vermellectomy
|
0/6
|
0/6
|
|
Tumor of the cheek mucosa
|
0/5
|
0/5
|
Small cervical lipoma
|
0/3
|
0/3
|
|
Floor of the mouth tumor
|
1/10
|
1/10
|
|
|
|
|
Tumor of the infrastructure of the maxilla
|
1/3
|
0/3
|
|
|
|
|
Salvage neck dissection
|
9/24
|
6/24
|
|
|
|
|
Branquial cyst surgery
|
2/30
|
2/30
|
|
|
|
|
Thyroglossal duct cyst resection
|
3/24
|
2/24
|
|
|
|
|
Cervical dermoid cyst
|
1/10
|
0/10
|
|
|
|
|
Big cervical lipoma
|
1/10
|
1/10
|
|
|
|
|
Submaxilectomy for benign tumors or lithiasis
|
6/22
|
6/22
|
|
|
|
|
Submaxilectomy for malignant tumors
|
1/3
|
1/3
|
|
|
|
|
Parotidectomy for benign tumors
|
24/106
|
4/106
|
|
|
|
|
Parotidectomy for malignant tumors
|
2/21
|
1/21
|
|
|
|
|
Skin cancer surgery
|
2/44
|
1/44
|
|
|
|
|
Rhinectomy
|
0/1
|
0/1
|
|
|
|
|
Microsurgery of the larynx
|
1/26
|
1/26
|
|
|
|
|
Secondary provox
|
2/6
|
2/6
|
|
|
|
|
Panendoscopy
|
0/8
|
0/8
|
|
|
|
Abbreviation: ER, emergency room.
Discussion
Readmissions are often indicative of ineffective patient management, raising questions regarding the quality of care provided and generating significant costs for the healthcare system.[13] Although some readmissions are unavoidable as a result of patient frailty or inevitable disease progression, others are preventable if patients receive the right care at the right time, reducing unnecessary readmissions.
Previous studies on head and neck cancer patients demonstrate the complex subset of these patients, who tend to be more frequently readmitted. Evaluating 155 total laryngectomy patients treated at one institution, Graboyes et al. found a 26.5% 30-day readmission rate.[11] Chaudhary et al. examined 1,518 elderly patients with oropharyngeal and laryngeal cancer from Medicare data in the USA and found that 14.1% of them were readmitted within the first 30 days of hospital discharge.[14] Chen et al. performed a retrospective cohort study of head and neck cancer patients based on the Nationwide Readmissions Database from the USA and reported a 16.1% overall readmission rate, with the highest readmission rates for patients with laryngeal (21.8%) and hypopharyngeal (29.6%) cancer.[15] Moreover, Bur et al. performed a retrospective analysis including data from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database looking for clinical risk factors and complications related to unplanned hospital readmission, reporting a rate of 5.1% of unplanned readmission in 2 years.[16] More recently, Baskin et al. highlighted the risk of return to the emergency room 30 days after surgery among patients who underwent head and neck surgery who needed to go to the intensive care unit.[7] In another study, Goel et al. demonstrated a higher rate of readmission in patients who underwent head and nek reconstruction after ablative surgery.[8] And Wu et al. in a study performed in Canada including patients who underwent head and neck surgery for benign and malignant disease, reported a rate of 3.2% of unplanned readmissions and of 8.4% of emergency room visits in the first 30 days after surgery.[9] Similarly, our study reports a 7.9% overall readmission rate for patients treated for benign or malignant pathology, and of 11.4% for patients treated by malignant disease, with the highest readmission rates for patients with laryngeal cancer (31.5%).
According to our data, the rate of unplanned readmission or the need to visit the emergency room during the first 30 days after hospital discharge was associated with major surgery, ASA classification status, and the type of wound, like in previous studies.[16] Malignant histology, ASA classification status, malnutrition, and length of hospitalization > 7 days were the factors related to an increased risk of readmission. The ASA classification status, malnutrition, and length of hospitalization > 7 days were related to an increased risk of visit to the emergency room in the first 30 days after discharge. Previous data reported by Bur et al. demonstrated that the most common cause of unplanned readmissions after head and neck surgery were infectious, including wound infection or breakdown (24%) and pneumonia (6.4%). However, this study has some limitations because it examined readmissions starting from 30 days of the surgical date instead of the discharge date, which may underestimate the readmissions in the first 30 days after discharge for complex head and neck patients with prolonged hospital stays.[16] Meanwhile, in our cohort, surgical site infection (2.87%), wound seroma (1.07%), pain (2.15%), salivary fistula (1.07%), or dysphagia (1.07%) were the most common causes of unplanned readmission or visit to the emergency room for all patients treated by benign or malignant disease of the head and neck.
Chen et al. evaluated patient comorbidities and showed that valvular heart disease, rheumatoid arthritis or collagen vascular disease, liver disease, and hypothyroidism were independently associated with readmission. They hypothesize that most readmissions are due to infectious and wound healing issues and, for that reason, these comorbidities become particularly important. They suggest that rheumatoid arthritis and collagen vascular disease are markers of long-term steroid use and chronic immunosuppression, and that these comorbidities can be related to unplanned readmission.[15] Similarly, Graboyes et al., in a previous study, found that long-term steroid use was associated with readmission in laryngectomy patients.[11] Furthermore, hypothyroidism and liver disease can contribute to difficulties in wound healing.[17]
[18] In our cohort, comorbidities such as diabetes, hypertension, obesity, COPD, or chronic cardiac disease were not associated with readmission. However, due to previously reported data, the need for an evidence-based risk stratification of the patients can be essential to improve decision-making and resource utilization. In this way, further investigation is needed to understand risk factors for unplanned hospital readmission after head and neck surgery. Strategies in future research need to include and report tools like the Charlson Comorbidity Index[19] and to classify the patients routinely according to the Clavien and Dindo Classification.[20]
Another critical issue related to unplanned readmission is the cost to the healthcare system. Chen et al. report 30-day readmission costs of US$14,895 (€16,860) on average for all payers in the USA,[15] similarly to prior data reported by Chaudhary et al. on Medicare patients, which demonstrated that oropharyngeal and laryngeal cancer patients who were readmitted had mean costs that were US$15,123 (€17,120) higher than those who were not readmitted.[14] Across European countries, healthcare providers are almost public, being necessary for the otorhinolaryngology-head and neck departments to evaluate their results and make some interventions aimed to improve them and to improve their savings, if necessary.
According to our data, the majority of readmissions are related to minor problems requiring only short hospital stays, and the significant financial impact over departments suggests that this is an area where some strategies can produce potential savings. In this way, avoiding preventable complication needs to be the primary objective in the postoperative period, translating this into a direct impact on the quality of life of our patients after discharge. Intervention over the risk of deep-vein thrombosis or venous thromboembolism, the correct use of antibiotics, implementation of protocols to assess the risk of dysphagia or silent aspiration aimed to prevent aspiration pneumonia, the correct dosage of nonsteroid anti-inflammatory drugs or corticosteroids and the use of proton pump inhibitors needs to be implemented. Moreover, as proposed by Danino et al. some possible ways to improve the rate of readmission can be a better patient or caregiver education related to possible complications, which can be done using written information describing postoperative symptoms and alarm signs, giving contact information to solve doubts, providing adequate analgesia to improve the quality of patient care, administering antibiotics in cases in which they may be needed, including a postoperative follow-up telephone call, and improving the training of emergency doctors in postoperative care of head and neck tumor patients to manage nonemergency complication, preventing the need for reattendance or potential readmission.[5]
Finally, a limitation in our study can be the small sample size compared with previous retrospective studies and the lack of cost-related analysis. For that reason, we decide to expand the duration of our study to evaluate and report more extensive data in the future to try to define strategies to avoid readmission for head and neck cancer surgery patients and perform a cost-related analysis.
Conclusion
Major surgery, ASA status and the type of wound are conditions related to unplanned readmission or visit to the emergency room in the first 30 days after discharge. The most common associated causes are infections or wound complications. In this way, an evidence-based risk stratification of the patients can be an essential tool to improve decision-making and resource utilization, and some educational strategies can provide ways to improve the rate of readmission, reducing the amount of money expended by healthcare systems.
