Keywords:
Prostatic neoplasm - Diagnostic-related groups - Bone metastasis - Length of stay.
Descritores:
Neoplasia prostática - Grupos de diagnósticos relacionados - Metástase óssea - Tempo
de permanência.
INTRODUCTION
Diagnosis-related group (DRG) is a classification based on patient diagnosis and illness
severity that is used as a care performance indicator and to analyze hospital costs.([1]) In the United States, it has been used as a system of prospective payment for Medicare
reimbursement since the 1980's.([2]) Moreover, as new technologies and treatments have been developed, the DRGs have
been updated, with several new editions published over the years.([3]) In Brazil, however, the DRG system has only been implemented in the last 10 years,
which is consistent with the epidemiological reality of the country.
Prostate cancer (PCa) is one of the most common malignancies in men worldwide.([4]) Tumor stage and patient performance status dictate the treatment strategy, which
may vary from surgery and radiotherapy with curative intent to chemotherapy and androgen-deprivation
therapy (ADT) for disease control in the metastatic setting.([5]) Several promising options have emerged for later-line treatment of recurrent or
metastatic PCa. Recent clinical trials with abiraterone and enzalutamide have demonstrated
benefits regarding overall survival, while apalutamide also showed increased metastasis
free-survival in castration-resistant PCa (CRPCa).([6]
[7]
[8]
[9]) However, new treatments and longer survival have been associated with increased
costs, especially in patients with metastatic cancer. One recent study estimated that
health costs have been increasing by almost US$9,000 per month per patient when using
new lines of treatment.([10]) Additionally, patients with PCa diagnosed with bone metastasis now have a mean
overall survival of 7.5 years.([11])
Although several parameters have a higher impact on case-mix weight and are associated
with increased hospital costs, length of stay (LOS) is among the most important variables
of interest during hospitalization that are used by the DRG system. Increased LOS
may be caused by disease-related factors or hospital-related circumstances, such as
access to healthcare or even the day of the week a patient is admitted.([8]) For example, Panagiotopoulos et al. (ANO)(x) analyzed oncologic DRGs in an internal medicine department and found that LOS was
the main factor for hospital under-reimbursement. Furthermore, inpatient facility
costs are the largest component of medical resource utilization in patients with metastatic
PCa, demonstrating that disease progression is directly associated to a higher economic
impact.([12])
It is well established that patients with PCa with or without metastasis demand an
increased amount of financial resources, mainly because of new treatment technologies,
prescription of novel drugs, or the presence of skeletal-related events.([13]) However, it is not completely understood whether the DRG system is able to predict
and explain the differences in LOS in case-mix groups.([14]) To date, there are no data comparing length of hospitalization for any cause in
patients with PCa, with or without metastasis, adjusted by confounders. Therefore,
we sought to compare whether hospital admissions of patients diagnosed with PCa and
bone metastasis are associated with increased LOS when compared to DRG- estimated,
in a population of patients receiving regular outpatient care who required hospital
admission for any cause.
MATERIAL AND METHODS
Study sample
We reviewed data from medical records of subjects previously diagnosed with PCa who
were admitted to Hospital Moinhos de Vento, Porto Alegre, Brazil. The eligibility
criteria were diagnosis of any stage PCa, regular care at the outpatient clinic at
the time of data collection, and hospitalization for any cause during the years 2018
and 2019. All patients were DRG-scored using the Brazilian DRG system that is coded
by major diagnostic categories, clinical or surgical admission and comorbidities,
and generates an estimate LOS.([1]) Patients coming from outside facilities were excluded. A total of 86 hospitalizations
were included, and no patient was excluded during analysis. Hospitalization longer
than estimated by DRG (>DRG-LOS) was described as a LOS of at least 1 day longer than
that estimated by the system.
Statistical analysis
The objective of the study was to evaluate the association among LOS, LOS estimated
by DRG, and presence of bone metastasis in patients with PCa. Patients were divided
into 2 groups: LOS=DRG-LOS (actual LOS shorter than or equal to that estimated by
DRG, group 1); or LOS>DRG-LOS (actual LOS longer than that estimated by DRG, group
2). Comparisons of baseline characteristics between groups 1 and 2 were performed
using chi-squared test for categorical variables and Student's t-test for continuous
variables baseline characteristics evaluated were: age (continuous in years), body
mass index (BMI, continuous in kg/m2), type of admission (dichotomous, clinical or
surgical), presence of comorbidities (dichotomous, >2 or = 2 comorbidities), intensive
care unit (ICU) admission during hospitalization (dichotomous, yes or no) and bone
metastasis (dichotomous, yes or no). The association of group 2 and presence of metastasis
was evaluated using logistic regression in univariable and multivariable analyses,
controlling for baseline covariates (age, BMI, type of admission, ICU admission, and
presence of comorbidities). Statistical analyses were performed using SPSS version
21; p <0.05 was considered to indicate statistical significance.
RESULTS
A total of 86 hospital admissions were studied. Mean age was 76.6 (±9.4) years, and
mean BMI was 25.9 (±5.8) kg/m2 ([Table 1]). Among all medical hospitalizations, urology was the most commonly represented
specialty, accounting for 31.4% (27 admissions), followed by clinical oncology with
30.2% (26 admissions) (Supplementary[Table 1]). The most frequent ICD-10 on hospitalization was PCa (N=24); however, there were
50 different ICD-10 codes described at admission (Supplementary[Table 2]). Mean LOS was significantly higher in the overall sample when compared to estimated
DRG-LOS (7.5±7.3 and 4.4±2.9, p =0.014) (Supplementary[Table 3]). Group 2 (LOS>DRGLOS) was significantly associated with admission for clinical
treatment (OR=3.54, 95% CI=1.40-8.91, p =0.007) and admission at ICU during hospitalization (OR=5.37, 95% CI=1.58-17.8, p =0.007). ([Table 2]). The prevalence of bone metastasis in groups 1 and 2 was 31.1% and 68.3%, respectively.
Bone metastasis was positively associated with group 2 status (LOS>DRGLOS) on univariable
and multivariable analysis (OR=4.76, 95% CI=1.91-11.8, p =0.001 and OR=3.48, 95% CI=1.08-11.2, p =0.03, respectively) ([Table 3]). Others baseline characteristics were not significantly different between groups
1 and 2. All patients were alive at discharge.
Table 1
Baseline characteristics.
|
Variables
|
LOS Group 1
|
Group 2
|
p
|
|
N (%)
|
45 (52.3)
|
41 (47.7)
|
--
|
|
Age (years), mean (SD)
|
74.9 (9.6)
|
78.3 (9.0)
|
0.610
|
|
BMI (kg/m2 ), mean (SD)
|
25.9 (5.5)
|
25.8 (6.1)
|
0.520
|
|
Admission-DRG, N (%)
|
|
|
0.006
|
|
Clinical
|
21 (46.7)
|
31 (75.6)
|
|
|
Surgical
|
24 (53.3)
|
10 (24.4)
|
|
|
ICU admission, N (%)
|
|
|
0.007
|
|
Absent
|
41 (69.3)
|
27 (39.7)
|
|
|
Present
|
4 (22.2)
|
14 (77.7)
|
|
|
Comorbidities, N (%)
|
|
|
0.780
|
|
=2
|
33 (73.3)
|
29 (70.7)
|
|
|
>2
|
12 (26.7)
|
12 (29.3)
|
|
|
Bone metastasis, N (%)
|
|
|
0.001
|
|
Absent
|
31 (68.9)
|
13 (31.7)
|
|
|
Present
|
14 (31.1)
|
28 (68.3)
|
|
BMI: Body mass index; SD: Standard deviation; DRG: Diagnosis-related groups; ICU:
Intensive care unit.
Table 2
Association between baseline characteristics and group 2 (actual LOS>LOS estimated
by DRG).
|
Variable
|
OR
|
95% CI
|
p
|
|
Age (years)
|
1.04
|
0.99-1.09
|
0.099
|
|
BMI (kg/m2 )
Admission-DRG
|
0.99
|
0.92-1.07
|
0.920
|
|
Surgical
|
ref.
|
--
|
--
|
|
Clinical
Comorbidities
|
3.54
|
1.40-8.91
|
0.007
|
|
=2
|
ref.
|
--
|
--
|
|
>2
ICU admission
|
0.87
|
0.34-2.25
|
0.788
|
|
Absent
|
ref.
|
--
|
--
|
|
Present
|
5.37
|
1.58-17.8
|
0.007
|
BMI: Body-mass index; CI: Confidence interval; OR: Odds ratio; IUC: Intensive unit
care; ref.: Reference.
Table 3
Association between LOS and presence of metastasis.
|
LOS
|
Bone metastasis
|
Univariable
|
Multivariable
|
|
Absent
|
Present
|
OR
|
95%CI
|
p
|
OR
|
95%CI
|
p
|
|
Group 1
|
31 (68.9)
|
14 (31.1)
|
ref.
|
--
|
--
|
ref.
|
--
|
--
|
|
Group 2
|
13 (31.7)
|
28 (68.3)
|
4.76
|
1.91-11.8
|
0.001
|
3.48
|
1.08-11.2
|
0.03
|
LOS: Length of stay; CI: Confidence interval; OR: Odds ratio; ref.: Reference.
DISCUSSION
DRGs are one of the most important tools to analyze optimal allocation of medical
resources in healthcare systems.([1]) First utilized in the U.S. in the 1980s, DRG coding started to be used in healthcare
systems in several other countries in the last decades.([15]) DRGs are formulated based on the diagnosis (divided into major diagnostic categories),
type of admission (clinical or surgical), and comorbidities, which generate codes
and estimate LOS for each case.([1]
[16]) More recently, this system has been used to support quality improvements and the
achievement of higher efficiency in healthcare.
PCa has an important impact on financial resources utilization due to its high prevalence
and incidence. Worldwide, more than 1.3 million patients were diagnosed with PCa in
2018 alone.([4]) In addition, major advances in treatments with curative intent and new medications
to manage disease recurrence or control metastasis have not only improved overall
survival and quality of life, but also increased costs.([11]) However, whether the presence of recurrent PCa or metastatic disease has any impact
on the homogeneity of DRG system categorization is still a matter of debate. Therefore,
we sought to evaluate whether patients with PCa and bone metastasis had a longer actual
LOS when compared to estimated DRG-LOS on admission when hospitalized due to any cause.
We found that admissions of patients with PCa and bone metastases were significantly
associated with increased duration of hospitalization when compared to the estimated
DRG-LOS.
LOS is an important metric to evaluate costs in healthcare.([17]) Additionally, some studies have demonstrated that LOS may be associated with increased
costs of clinical and surgical hospitalizations.([8]
[18]
[19]) For instance, Fine et al. (2000),([18]) in a multicenter study analyzing patients admitted with community-acquired pneumonia,
revealed considerable cost savings with as little as a 1-day reduction in LOS. Moreover,
a recent review of 37 studies indicated that enhanced recovery programs versus conventional
management decreased the LOS after abdominal surgeries and were substantially associated
with cost savings.([19]) It seems that duration of hospitalization is directly correlated with consumption
of health resources.
Although the majority of patients at the time of PCa diagnosis have localized disease,
almost 30% will develop bone metastasis during follow-up.([20]) In our study, among all admissions, PCa with bone metastasis was present in 42
(48.8%) and was independently associated with increased LOS. As long as patients with
metastatic PCa have access to adequate treatment (androgen deprivation therapy), long
overall survival and even increased metastasis free-survival can be expected for this
group. Data from CaPSURE, which analyzed more than 12,000 patients from 1990 to 2004,
found that PCa-specific survival at 5 years was 71% (95% CI=62-78).([11]) A recent double-blind clinical trial that studied the androgen receptor inhibitor
apalutamide in non-metastatic castration-resistant PCa found a significant survival
free of metastasis when compared to placebo (HR 0.28; 95% CI=0.23-0.35).([21]) Thus, given the fact that, in our study, PCa with bone metastasis was associated
with a 3.48-fold increase in risk for longer LOS even after adjusting for other variables,
it is plausible to think that new medications that prevent development of bone metastases
may also lead to shorter LOS when these patients are hospitalized.
Analysis of patient characteristics that may increase or decrease LOS is of interest
for hospital reimbursements and performance analysis. Some studies have evaluated
factors that may influence these scenarios.([12]
[16]) For example, in a large study that evaluated the duration of hospitalization of
patients with acute coronary syndromes, the authors found that diabetes and cerebrovascular
disease were directly associated with increased LOS, with a higher weight when compared
to other comorbidities, and concluded that the presence of this two diseases should
be linked to higher reim-bursement.([22]) In another study, Freitas et al. (2012),([23]) analyzed variables associated with LOS outliers in the Portuguese National Health
Service and found that addition of each comorbidity in the statistical model resulted
in an adjusted OR of 1.41. In our analysis, comorbidities were not correlated with
actual LOS higher than estimated DRG-LOS. However, as we did not analyze specific
types of comorbidities, further studies are necessary to assess the real impact of
specific medical conditions during hospitalization in PCa patients.
Our study has some limitations. First, our data were collected from a single private
hospital. Second, we selected only patients who were receiving regular outpatient
follow-up at our clinic, to ensure data quality. Notably, the majority of patients
who were hospitalized at our institution came from outside facilities, which restricted
the number of admissions in our sample. Third, DRG coding and data were collected
retrospectively. Finally, we did not study types of comorbidities or severity of bone
disease, as indicated by pain or number of metastases.
CONCLUSION
To the best of our knowledge, this was the first study to analyze the association
between LOS estimated by DRG and PCa. We found that, among admissions of patients
diagnosed with PCa, the presence of bone metastasis was independently associated with
significantly longer actual LOS when compared with LOS estimated by DRG. This finding
has implications for hospital resources allocation and efficiency analysis. The advent
of new medications that increase metastasis-free survival in patients diagnosed with
recurrent non-metastatic PCa may decrease LOS when these patients are hospitalized.
The presence of bone metastases may be used to identify possible outliers who are
not recognized by the DRG system.
Supplementary Table 1
Admissions by medical specialty.
|
Medical specialty
|
N(%)
|
|
Oncology
|
26(30.2)
|
|
Cardiology
|
7(8.1)
|
|
General surgery
|
2(2.3)
|
|
Thoracic surgery
|
1(1.2)
|
|
Vascular surgery
|
2(2.3)
|
|
Internal medicine
|
12(14.0)
|
|
Proctology
|
1(1.2)
|
|
Gastroenterology
|
1(1.2)
|
|
Infectious diseases
|
2(2.3)
|
|
Nephrology
|
3(3.5)
|
|
Neurosurgery
|
1(1.2)
|
|
Neurology
|
1(1.2)
|
|
Urology
|
27(31.4)
|
|
Total
|
86(100)
|
BMI: Body-mass index; CI: Confidence interval; OR: Odds ratio; IUC: Intensive unit
care; ref.: Reference.
Supplementary Table 2
International Classification of Diseases (ICD) to each patient admission.
|
|
Description
|
N(%)
|
|
|
|
Aortic aneurysm
|
2(2.4)
|
|
|
|
Aneurysm of artery of lower limb
|
1(1.2)
|
|
|
|
Unstable angina
|
2(2.4)
|
|
|
|
Aortic stenosis
|
1(1.2)
|
|
|
|
Pneumonia
|
2(2.4)
|
|
|
|
Cystitis
|
1(1.2)
|
|
|
|
Ureteral calculus
|
1(1.2)
|
|
|
|
Acute proctitis
|
1(1.2)
|
|
|
|
Unspecified complications of medical care
|
1(1.2)
|
|
|
|
Pleural effusion
|
1(1.2)
|
|
|
|
Disorientation
|
1(1.2)
|
|
|
|
Pain in limb
|
1(1.2)
|
|
|
|
Pulmonary embolism
|
2(2.4)
|
|
|
|
Urethral stenosis
|
1(1.2)
|
|
|
|
Atrial fibrillation
|
2(2.4)
|
|
|
|
Hematuria
|
2(2.4)
|
|
|
|
Bilateral inguinal hernia
|
2(2.4)
|
|
|
|
Hypo-osmolality and hyponatremia
|
1(1.2)
|
|
|
|
Phimosis
|
1(1.2)
|
|
|
|
Hypotension
|
1(1.2)
|
|
|
|
Male erectile dysfunction
|
1(1.2)
|
|
|
|
Myocardial infarction
|
1(1.2)
|
|
|
|
Cerebral infarction
|
1(1.2)
|
|
|
|
Urinary tract infection
|
1(1.2)
|
|
|
|
Congestive heart failure
|
2(2.4)
|
|
|
|
Acute kidney failure
|
2(2.4)
|
|
|
|
Malignant neoplasm of prostate
|
21(26.8)
|
|
|
|
Malignant neoplasm of rectum
|
1(1.2)
|
|
|
|
Malignant neoplasm, unspecified
|
1(1.2)
|
|
|
|
Malignant neoplasm of pancreas
|
1(1.2)
|
|
|
|
Malignant neoplasm of ureter
|
1(1.2)
|
|
|
|
Malignant neoplasm of bladder
|
2(2.4)
|
|
|
|
Malignant neoplasm of stomach
|
1(2.4)
|
|
|
|
Malignant neoplasm of lung
|
2(2.4)
|
|
|
|
Secondary malignant neoplasm of bone marrow
|
4(4.8)
|
|
|
|
Joint disorders
|
1(1.2)
|
|
|
|
Pathological fracture
|
2(2.4)
|
|
|
|
Unspecified bowel obstruction
|
1(1.2)
|
|
|
|
Gastroenteritis and colitis, unspecified
|
1(1.2)
|
|
|
|
Retention of urine
|
2(2.4)
|
|
|
|
Acute prostatitis
|
1(1.2)
|
|
|
|
Infection due to a procedure
|
1(1.2)
|
|
|
|
Septicemia, unspecified
|
3(3.6)
|
|
|
|
Chemotherapy session
|
1(1.2)
|
|
|
|
Cervical disk disorder with radiculopathy
|
1(1.2)
|
|
|
|
Disorder of urinary system, unspecified
|
1(1.2)
|
|
|
|
Esophageal varices with bleeding
|
2(1.2)
|
|
|
Measures of central tendency
|
Actual LOS
|
DRG-LOS
|
|
p
|
|
Mean
|
|
7.55
|
4.3860
|
|
<0.001
|
|
Median
|
|
5.00
|
3.6500
|
|
|
|
Percentile
|
25
|
3.00
|
2.1000
|
|
|
|
50
|
5.00
|
3.6500
|
|
|
|
75
|
11.00
|
6.6000
|
|
|
|
Total
|
|
|
|
86(100)
|
|
Bibliographical Record
Daniel Melecchi Freitas, Isabelle W Zorzo, Gisele Bastos Nader, Eduardo Franco Carvalhal,
Jussara Maccari, Luiz Nasi, Mauro Weiss. Estimated length of stay calculated by “diagnosisrelated
groups” in patients with prostate cancer: a retrospective analysis. Brazilian Journal
of Oncology 2021; 17: e-20210004.
DOI: 10.5935/2526-8732.20210004
