The cross-sectional study, conducted in 2023, was carried out at a general hospital in Tabriz, Iran. This hospital is the second-largest private healthcare facility in northwest Iran, encompassing 11 specialized departments, including CCU, General ICU, Medical ICU, Lung ICU, NICU, Pediatrics, Obstetrics and Gynecology, Internal Medicine, Orthopedics, and Cardiac Surgery. The hospital is equipped with 179 active beds and serves an annual patient population exceeding 16,000.
A comprehensive census approach was employed to include all 16,071 patients admitted to the hospital between 21 March 2021 and 20 March 2022. Additionally, the study involved 137 attending physicians in its scope. Vital information was gathered from the electronic records in the hospital Information System (HIS) and compiled into an Excel spreadsheet. This data encompassed both social and clinical details, such as age, sex, definitive disease diagnosis, insurance type, and the attending physician. The diseases were categorized into 22 distinct groups based on the International Classification of Diseases 10th Revision (ICD-10). For streamlined data analysis, these disease categories were further condensed into six groups, a classification arrived at through consensus among five physicians, each with expertise in different medical specialties. These six groups were identified as follows:
(1) Blood and cancer-related diseases; (2) internal diseases; (3) psychiatric and neurological disorders; (4) ear, nose, throat, and eye conditions; (5) gynecological issues, obstetrics, fetal, and neonatal abnormalities; (6) other diseases.
Patients were categorized into six distinct groups based on their insurance coverage. This classification involved three primary insurance entities prevalent in Iran: Social security insurance (Tamin Ejtemaei), health insurance (Salamat), and armed forces insurance (Niroohaye Mosallah) (
11). Additionally, two more groups were established, one for individuals with rural insurance (Roostayi) and another for patients covered by alternative insurance funds. Lastly, a separate group was designated for individuals lacking any form of insurance coverage.
The data collected from the physicians encompassed details such as age, sex, their area of expertise (surgeon or non-surgeon), their level of specialization (whether they were specialists or subspecialists), their professional experience, and the type of contractual arrangement they had (either as guests or shareholders).
To ensure the privacy and confidentiality of both patients and physicians, sensitive identity information like first names, last names, and national identification codes was redacted from the records. Instead, each patient and physician was assigned a unique code for the purpose of data analysis, thereby safeguarding their personal information.
To investigate the predictors of DAMA, a multilevel modeling approach was applied to simultaneously examine patient- and physician-level variables. Multilevel modeling offers several benefits, including the ability to account for nested data structures, such as patients within physician groups, thereby capturing the hierarchical nature of healthcare data. Additionally, it allows for the simultaneous examination of both patient-level and physician-level variables within a unified analytical framework, providing a more comprehensive understanding of the factors influencing discharge against medical advice (DAMA).
3.1. Statistical Analysis
The data were presented using descriptive statistics, including mean ± standard deviation for quantitative data and median (Q1 - Q3) for qualitative data. A multilevel analysis approach was employed to examine the influence of patient- and physician-related variables on the likelihood of DAMA. Multilevel models are particularly suitable for handling complex data structures with nested levels. Unlike single-level models, such as simple regression, which assume independence of observations, multilevel models account for dependencies in nested data structures, such as when patients are nested within physician groups (
12).
A generalized multilevel model akin to traditional linear regression was utilized. The primary distinction lies in the acknowledgment that observations are not assumed to be independent in linear multilevel modeling (
12). Consequently, the multilevel analysis model was instrumental in partitioning the variance at the patient level due to the effects attributed to physician-level factors.
To explore the association between individual factors (variables at the patient level) and physician factors (variables at the physician level) with DAMA, a two-level random-intercept Poisson model was employed. Data analysis was conducted using Stata software version 16, and statistical significance was determined with a p-value threshold of less than 0.05.
Two-level logistic regression model:
The two-level logistic regression model with a random intercept is defined as follows for modeling the response variable (denoted as Y) with p predictors at level 1 and q predictors at level 2 (
13,
14):
Here, is the probability of patient i being discharged against medical advice when treated by physician j. The model includes fixed effects (β00, βi0, β0j) related to level one and level two predictors, and a random effect () with a normal distribution having mean zero and variance . In this model, is interpreted as the odds of DAMA.
Three models were examined: First, a null model (no predictors included), then a model with patient-level variables, and finally a Full model incorporating all level one and level two variables for the data. The addition of variables in the three models was assessed using -2log likelihood and the Likelihood Ratio Test (LRT).