Summary
Objectives:
Pulmonary embolism (PE) is a potentially fatal condition among hospitalised patients, with a prevalence of approximately 1.0%. PE is associated with high morbidity and mortality. This study aimed to identify patient characteristics and risk factors related to the development, recurrence, and mortality of PE in hospitalised patients at Sultan Qaboos University Hospital (SQUH), Muscat, Oman.
Methods:
This retrospective cohort study was conducted at SQUH, involving patients diagnosed with PE during admission between January 2015 and December 2019. Data were collected from electronic patient records, including demographic details, comorbidities, risk factors and healthcare outcomes. Pulmonary Embolism Severity Index (PESI) scores were calculated. Statistical analyses were performed to identify predictors of mortality and recurrence of PE.
Results:
A total of 192 patients diagnosed with PE were included in this study; 16.7% died during the index admission. Older age, higher PESI scores, central venous access and autoimmune disease were significant independent predictors of inpatient mortality. The recurrence rate of PE was 9.5% during the follow-up period, with no significant association between patient characteristics and recurrence. This study also highlighted the prevalence of risk factors such as reduced mobility, recent hospitalisation, obesity and infection among the cohort.
Conclusion:
This research contributes to the knowledge of PE recurrence, mortality and associated risk factors. Hypertension, diabetes and chronic heart failure are common comorbidities in PE patients. Older age, higher PESI scores, central venous access and autoimmune disease were significant predictors of mortality.
Keywords: Pulmonary Embolism, Mortality, Recurrence, Risk, Anticoagulation, Oman
Advance in Knowledge
Older age, higher PESI scores, central venous access and autoimmune disease are all independent indicators of mortality risk.
The risk factors for pulmonary embolism (PE) were reduced mobility, recent hospitalisation, obesity and infection.
The PE recurrence rate in the current cohort is comparable to previous studies.
No significant association between patient characteristics and PE recurrence was found.
Application to Patient Care
In clinical practice, applying existing tools such as the Wells score and PESI to improve detection and predict the severity of PE is crucial.
In the current setting, it is essential to consider implementing deep venous thrombosis prophylaxis measures for hospitalised patients who have known risk factors for PE, focusing on factors such as reduced mobility, recent hospitalisation, obesity and infection.
1. Introduction
Pulmonary embolism (PE) is a significant and potentially life-threatening condition that can occur among hospitalised patients. The prevalence of acute PE in a general hospital setting is approximately 1.0%.1 Among patients who died in the hospital, PE was found in 14.6% of autopsies, with 37.3% of these cases being the direct cause or a contributing factor to death.1 Among patients hospitalised for a first episode of syncope, the prevalence of PE was 17.3%.2 The incidence of PE in patients with severe decompensated congestive heart failure admitted to coronary care units is 9.1%, a figure that remains high despite adequate DVT prophylaxis.3
Despite high levels of pharmacological thromboprophylaxis, certain hospitalised populations still exhibit a high incidence of PE. Older age and female gender are associated with a higher prevalence of PE in hospitalised patients.4 Underlying health conditions such as chronic obstructive pulmonary disease (COPD), heart diseases and obesity are linked to an increased risk of PE.4,5 Surgical operations, especially major surgeries and trauma, particularly multiple lower-extremity and pelvic fractures, significantly elevate the risk of PE.5 Elevated levels of D-dimer, C-reactive protein (CRP) and other inflammatory markers at admission are independent predictors of PE in patients hospitalised for COVID-19 infection.6 Prolonged immobility, intensive care unit (ICU) admission and mechanical ventilation are associated with higher PE rates during hospitalisation.7
PE is a serious medical condition with a significant risk of recurrence, which contributes to higher rates of morbidity and mortality. Recurrence factors include long-term immobility, hospitalisation and chronic conditions such as COPD and cancer.6,7 Additional risks include unprovoked PE, varicose veins, coexisting atrial fibrillation (shared risk factors: old age, obesity, heart failure) and particular ICU-related conditions. In patients with trauma, lower limb fractures, obesity and older age are typically associated with early post-traumatic PE, increasing mortality and ICU stays.8
Older age and the presence of comorbid conditions such as COPD, heart failure and atrial fibrillation significantly increase the risk of mortality in PE patients.7 Right ventricular dysfunction and elevated troponin levels are correlated with higher short-term mortality, even in patients initially classified as low-risk. Elevated serum levels of biomarkers such as N-terminal pro B-type natriuretic peptide, low haemoglobin and high blood urea nitrogen are linked to worse outcomes. The presence of a bifurcation thrombus and reduced left ventricular ejection fraction are also associated with high in-hospital mortality.7
This study aimed to comprehensively identify patients' characteristics and risk factors associated with the development, recurrence and mortality of PE among hospitalised patients.
2. Methods
This is a retrospective cohort study included patients diagnosed with PE during their admission to the medical and surgical ward between January 2015 and December 2019 at Sultan Qaboos University Hospital (SQUH), Muscat, Oman. SQUH is a tertiary centre with a 700-bed capacity, of which 56 beds are located in the medical wards. The average daily admission rate in the medical wards is approximately 12 patients. Treatment for PE, which varies in severity, often involves anticoagulation, catheter-directed thrombolysis, thrombectomy and/or thrombolysis. PE patients are usually referred by phone call and through electronic patient records. All computed tomography pulmonary angiography (CTPA) scans performed during the study period for the diagnosis of PE were reviewed, and patients with a positive PE diagnosis were included in the study.
The following data were collected from the patient's electronic records: age, gender, comorbidities (e.g., diabetes mellitus, hypertension, heart failure), length of hospital stay, type of admission (medical versus surgical) and type of anticoagulation. Additionally, variables deemed relevant according to the risk factors from the 2019 European Society of Cardiology/European Respiratory Society (ECS/ERS) Guidelines for the diagnosis and management of acute PE were also considered.9 These factors included reduced mobility, recent hospitalisation (within 3 months of PE development), previous venous thromboembolism (VTE), thrombophilia, obesity, inflammatory bowel disease, active malignancy, autoimmune diseases, recent surgery or trauma, central venous access, hormone replacement therapy, oral contraceptive pills, post-partum period, infection and pregnancy.
Pulmonary Embolism Severity Index (PESI) scores were calculated to assess the severity of PE.10 The severity of PE was classified as low, intermediate and high risk according to the risk stratification by ESC/ERS Guidelines for the diagnosis and management of acute PE.9 Data about the type and duration of anticoagulation were gathered. Healthcare outcomes were ascertained by reviewing the electronic patient information records or conducting phone follow-ups.
Continuous variables were expressed as mean ± standard deviation for normally distributed data or median/interquartile range (IQR) for non-normally distributed data. The Shapiro-Wilk test was used to confirm the normality of continuous variables. Continuous variables between the 2 groups were compared using the student's t-test for normally distributed variables or the Wilcoxon rank-sum test for non-normally distributed variables. Categorical variables were reported as numbers and percentages. The Chi-squared test or Fisher's exact test was used to assess the association between categorical variables as appropriate. Relevant clinical characteristics were included in backward stepwise regression analysis multivariable logistic regression to identify independent predictors associated with increased mortality. Odds ratios (ORs) were calculated with 95% confidence intervals (CIs); 2-sided P values of <0.05 were considered statistically significant. The Kaplan-Meier analysis was used to determine time to PE recurrence. at the point of analysis were censored at their last follow-up date. Statistical calculations were performed using the Stata (StataCorp LLC, College Station, Texas, USA) Version 17.1 software package.
3. Results
A total of 1,682 CTPAs were performed for suspected PE during the study period of which 192 patients were found to have PE (11.4%, 95% CI: 9.9–12.9%). The median age was 61 years (IQR: 41–72), with women comprising 56.3% (n = 108) of the cohort. Hypertension was prevalent in 46.4% (n = 89) and 42.2% (n = 81) had reduced mobility. Recent hospitalisation was documented in 38% (n = 73) of patients. Obesity was found in 30.7% of patients (n = 59), while 16.7% (n = 32) had active malignancy. Most admissions were medical (79.6%, n = 153) and 20.3% (n = 39) being surgical. The median simplified PESI score was 2 (IQR: 1–2) and the median severity of PE was intermediate (IQR: low–intermediate). The in-hospital mortality rate was 16.7% (n = 32) while the recurrence rate of pulmonary embolism was 7.3% (n = 14), with a median anticoagulation duration of 90 days (IQR: 14–90) [Table 1].
Table 1.
Characteristics and risk factors of patients admitted with pulmonary embolism (N = 192).
| Characteristic | n (%) |
|---|---|
| Median age in years (IQR) | 61 (41–72) |
| Women | 108 (56.3) |
| Hypertension | 89 (46.4) |
| Diabetes mellitus | 64 (33.3) |
| Chronic heart failure | 42 (21.9) |
| Risk factors for thromboembolism | |
| Reduced mobility | 81 (42.2) |
| Recent hospitalisation | 73 (38) |
| Thrombophilia | 7 (3.7) |
| Obesity | 59 (30.7) |
| Inflammatory bowel disease | 4 (2.1) |
| Active malignancy | 32 (16.7) |
| Autoimmune disease | 10 (5.2) |
| Chronic heart failure | 42 (21.9) |
| Chronic lung disease | 22 (11.5) |
| History of thromboembolism | 20 (10.4) |
| History of surgery or trauma in the past month | 49 (25.5) |
| Central venous access | 17 (8.9) |
| Hormone replacement therapy | 0 (0) |
| Oral contraceptive pill | 6 (3.1) |
| Postpartum | 5 (2.6) |
| Pregnancy | 4 (2.1) |
| Infection | 51 (26.6) |
| Admission | |
| Medical admission | 153 (79.7) |
| Surgical admission | 39 (20.3) |
| Median length of hospital stay in days (IQR) | 12 (7–19) |
| Median simplified PESI# (IQR) | 2 (1–2) |
| Median severity of PE*# (IQR) | 2 (1–2) |
| Direct oral anticoagulant | 75 (39.1) |
| Vitamin K antagonist | 41 (21.4) |
| Low molecular weight heparin | 57 (29.7) |
| Others† | 18 (9.4) |
| Median duration of anticoagulation in days (IQR) | 90 (14–90) |
| Died in hospital | 32 (16.7) |
| Reoccurrence of PE | 14 (7.3) |
IQR = interquartile range; PESI = Pulmonary Embolism Severity Index; PE = pulmonary embolism.
Severity of PE: 1 indicates low risk, 2 indicates intermediate risk and 3 indicates high risk using the risk stratification by ESC/ERS Guidelines for the diagnosis and management of acute PE.
Others = unfractionated heparin or fondaprinux.
A total of 32 patients (16.7%) died during the index admission. Death was more common among older patients (median age: 69.5 versus 59.0 years; P = 0.0083), non-obese patients (13.8% versus 36.4%; P = 0.014), patients with higher simplified PESI scores (median PESI score = 2.0 [IQR: 2.0–2.0] versus 2.0 [IQR: 1.0–2.0]; P = 0.0034) and patients admitted to the medical ward (96.7% versus 76.3%; P = 0.008) [Table 2].
Table 2.
Characteristics and risk factors of patients admitted with pulmonary embolism classified according to inpatient mortality (N = 192).
| n (%) | |||
|---|---|---|---|
|
|
|||
| Characteristic | Inpatient mortality (No, n = 160) | Inpatient mortality (Yes, n = 32) | P value |
| Median age in years (IQR) | 59.0 (40.0–71.2) | 69.5 (58.0–75.0) | 0.008 |
| Women | 93 (58.1) | 15 (46.9) | 0.242 |
| Hypertension | 76 (48.1) | 13 (40.6) | 0.477 |
| Diabetes mellitus | 57 (36.1) | 7 (21.9) | 0.132 |
| Chronic heart failure | 36 (23.1) | 6 (18.8) | 0.639 |
| Risk factors for thromboembolism | |||
| Reduced mobility | 67 (43) | 14 (43.8) | 0.934 |
| Recent hospitalisation | 66 (41.5) | 7 (21.9) | 0.039 |
| Thrombophilia | 6 (3.9) | 1 (3.2) | 0.863 |
| Obesity | 55 (36.4) | 4 (13.8) | 0.014 |
| Inflammatory bowel disease | 4 (2.5) | 0 (0) | 1.000 |
| Active malignancy | 22 (14) | 10 (31.3) | 0.015 |
| Autoimmune disease | 7 (4.5) | 3 (9.4) | 0.245 |
| History of thromboembolism | 17 (10.8) | 3 (9.4) | 0.816 |
| History of surgery or trauma in the past month | 49 (30.6) | 0 (0) | 0.000 |
| Central venous access | 12 (7.6) | 5 (15.6) | 0.147 |
| Hormone replacement therapy | 0 (0) | 0 (0) | |
| Oral contraceptive pill | 6 (3.8) | 0 (0) | 0.592 |
| Postpartum | 5 (3.1) | 0 (0) | 0.311 |
| Pregnancy | 4 (2.6) | 0 (0) | 1.000 |
| Infection | 43 (27) | 8 (25) | 0.812 |
| Admission | |||
| Medical admission | 122 (76.3) | 31 (96.7) | 0.008 |
| Surgical admission | 38 (23.8) | 1 (3.1) | 0.008 |
| Median length of hospital stay in days (IQR) | 12 (7–18) | 16.5 (6–38) | 0.0793 |
| Median simplified PESI (IQR) | 2.0 (1.0–2.0) | 2.0 (2.0–2.0) | 0.0034 |
| Median severity of PE* (IQR) | 2.0 (1.0–2.0) | 2.0 (1.0–3.0) | 0.5046 |
IQR = interquartile range; PESI = Pulmonary Embolism Severity Index; PE = pulmonary embolism.
Severity of PE: 1 indicates low risk, 2 indicates intermediate risk and 3 indicates high risk using the risk stratification by ESC/ERS Guidelines for the diagnosis and management of acute pulmonary embolism.
The stepwise backward regression analysis identified several significant predictors of mortality, including older age (OR: 1.049, 95% CI: 1.019–1.080; P = 0.001), higher simplified PESI scores (OR: 5.842, 95% CI: 1.181–28.891; P = 0.030), presence of central venous access (OR: 4.202, 95% CI: 1.054–16.759; P = 0.042) and autoimmune disease (OR: 6.247, 95% CI: 1.135–34.376; P = 0.035). Conversely, protective factors against mortality included female gender (OR: 0.337, 95% CI: 0.131–0.872; P = 0.025), obesity (OR: 0.179, 95% CI: 0.051–0.622; P = 0.007), recent hospitalisation (OR: 0.257, 95% CI: 0.088–0.752; P = 0.013) and chronic heart failure (OR: 0.237, 95% CI: 0.070–0.807; P = 0.021) [Table 3].
Table 3.
Multivariate regression analysis of risk factors for inpatient mortality in patients with pulmonary embolism.
| Variable | OR | 95% CI | P value | VIF |
|---|---|---|---|---|
| Age | 1.049 | 1.019–1.080 | 0.001 | 1.12 |
| Female gender | 0.337 | 0.131–0.872 | 0.025 | 1.08 |
| Length of hospital stay | 1.021 | 1.000–1.043 | 0.053 | 1.05 |
| Simplified PESI | 5.842 | 1.181–28.891 | 0.030 | 1.10 |
| Central venous access | 4.202 | 1.054–16.759 | 0.042 | 1.06 |
| Obesity | 0.179 | 0.051–0.622 | 0.007 | 1.03 |
| Recent hospitalisation | 0.257 | 0.088–0.752 | 0.013 | 1.04 |
| Autoimmune disease | 6.247 | 1.135–34.376 | 0.035 | 1.02 |
| Chronic heart failure | 0.237 | 0.070–0.807 | 0.021 | 1.07 |
OR = odds ratio; CI = confidence interval; VIF = variance inflation factor.
Backward stepwise selection was employed, with a removal criterion of P >0.05. Pseudo R2 = 0.2665; sensitivity = 35.59%; specificity = 90.77%; overall classification accuracy = 73.54%.
Regarding the recurrence of PE, 147 patients (excluding 32 deaths and 13 lost to follow-up) were followed for PE recurrence. The median follow-up duration was 56 months (IQR: 34–68 months). The median duration of anticoagulation was 90 days (IQR: 60–270 days), with the majority of patients (70.1%, n = 103) being anticoagulated for less than 6 months. Non-vitamin K antagonist oral anticoagulants were most commonly used among this cohort (76.2%, n = 112) [Table 4]. A total of 14 patients (9.5%) experienced a recurrence of PE during the follow-up period [Fig. 1]. Univariate analysis did not show statistically significant differences in patient characteristics, risk factors, duration of anticoagulation or type of anticoagulation between the groups with and without recurrent PE.
Table 4.
Patient characteristics, risk factors and treatment duration classified according to recurrence of pulmonary embolism (N = 147).
| n (%) | ||||
|---|---|---|---|---|
|
|
||||
| Characteristic | Total | Recurrence of PE (Yes, n = 14) | Recurrence of PE (No, n = 133) | P value |
| Median age in years (IQR) | 59 (40–72) | 41.5 (35–70) | 60 (41–72) | 0.29 |
| Women | 88 (59.9) | 5 (35.7) | 83 (62.4) | 0.05 |
| Median follow-up duration in months (IQR) | 56 (34–68) | 38 (34–56) | 56 (36–68) | 0.25 |
| Hypertension | 70 (48.3) | 5 (35.7) | 65 (49.6) | 0.32 |
| Diabetes mellitus | 53 (36.6) | 3 (21.4) | 50 (38.2) | 0.26 |
| Chronic heart failure | 32 (22.2) | 3 (21.4) | 29 (22.3) | 1.00 |
| Chronic lung disease | 16 (11) | 1 (7.1) | 15 (11.5) | 1.00 |
| Risk factors for thromboembolism | ||||
| Reduced mobility | 61 (42.7) | 4 (28.6) | 57 (44.2) | 0.40 |
| Recent hospitalisation | 57 (39) | 4 (28.6) | 53 (40.2) | 0.57 |
| Thrombophilia | 6 (4.2) | 1 (7.1) | 5 (3.9) | 0.47 |
| Obesity | 4 (34.8) | 6 (46.2) | 42 (33.6) | 0.37 |
| Inflammatory bowel disease | 4 (2.7) | 0 (0) | 4 (3) | 1.00 |
| Active malignancy | 22 (15.2) | 2 (14.3) | 20 (15.3) | 1.00 |
| Autoimmune disease | 7 (4.9) | 0 (0) | 7 (5.4) | 1.00 |
| History of thromboembolism | 15 (10.3) | 3 (21.4) | 12 (9.2) | 0.16 |
| History of surgery or trauma in the past month | 44 (29.9) | 5 (35.7) | 39 (29.3) | 0.62 |
| Central venous access | 11 (7.6) | 1 (7.1) | 10 (7.6) | 1.00 |
| Hormone replacement therapy | 0 (0) | 0 (0) | 0 (0) | |
| Oral contraceptive pill | 6 (4.1) | 0 (0) | 6 (4.5) | 1.00 |
| Postpartum | 4 (2.7) | 2 (14.3) | 2 (1.5) | 0.05 |
| Pregnancy | 3 (2) | 0 (0) | 3 (2.3) | 1.00 |
| Infection | 41 (28.1) | 2 (14.3) | 39 (29.6) | 0.35 |
| Admission | ||||
| Medical admission | 114 (76.6) | 12 (10.5) | 102 (89.5) | 0.74* |
| Surgical admission | 33 (22.4) | 2 (6) | 31 (93.9) | |
| Median length of hospital stay in days (IQR) | 12 (7–18) | 12 (5–17) | 12 (7–18.5) | 0.61 |
| Simplified PESI ± SD | 1.7 ± 0.5 | 1.7 ± 0.5 | 1.7 ± 0.5 | 0.77 |
| Severity of PE ± SD§ | 1.9 ± 0.7 | 1.7 ± 0.8 | 1.9 ± 0.7 | 0.63 |
| Median duration of anticoagulation in days (IQR) | 90 (60–270) | 135 (42–270) | 90 (90–270) | 0.83 |
| Duration of anticoagulation >6 months | 44 (29.9) | 4 (28.6) | 40 (30.1) | 1.00† |
| Duration of anticoagulation <6 months | 103 (70.1) | 10 (71.4) | 93 (69.9) | |
| Type of anticoagulation | ||||
| Vitamin K antagonist | 35 (23.8) | 4 (11.4) | 31 (88.6) | 0.74‡ |
| Non-vitamin K antagonist | 112 (76.2) | 10 (8.9) | 102 (91.1) | |
IQR = interquartile range; PESI = Pulmonary Embolism Severity Index; SD = standard deviation; PE = pulmonary embolism.
P value comparing recurrence of PE among medical admission versus surgical admission.
P value comparing the effect durations of anticoagulation >6 months versus duration of anticoagulation <6 months on PE recurrence.
P value comparing the effect vitamin K antagonist versus non-vitamin K antagonist on PE recurrence.
Severity of PE: 1 indicates low risk, 2 indicates intermediate risk and 3 indicates high risk using the risk stratification by ESC/ERS Guidelines for the diagnosis and management of acute pulmonary embolism.
Fig. 1.
Recurrence of pulmonary embolism in the current study.
4. Discussion
This study provides important data on the recurrence and risk factors of PE in the Arab region as there are minimal studies that focus on the recurrence of PE and related risk factors.
Positivity rates for PE using a CTPA test vary widely from 7–29.6% with a rate of 11.4% found in the current study.8,9 Adherence to protocols such as calculating Wells score and checking D-dimer levels can enhance positivity rates, which also show considerable variation across different sites and physicians.13 The use of D-dimer testing, patient characteristics including a history of DVT or clinical signs of DVT and repeat CTPA scans after an initial negative result can influence the positive rate. Conversely, conditions such as COPD are generally associated with lower positive rates.13
In the current study, the most prevalent comorbidities observed were hypertension, diabetes mellitus and chronic heart failure. Past studies have indicated that many PE patients frequently suffer from significant comorbidities such as hypertension, obesity and hyperlipidemia.10 Chronic conditions such as heart failure, chronic pulmonary disease and alcohol abuse have a strong correlation with an increased risk of complications in PE patients.11 Additionally, patients on chronic dialysis have a considerably higher likelihood of developing PE, independent of other health conditions.15
The most common risk factors among patients with PE in the current study were reduced mobility, recent hospitalisation, obesity and infection. Previous studies showed that sepsis, prolonged hospital stays, emergency admissions, cancer and abnormal coagulation markers were associated with increased risk of PE in an ICU setting.16 Increased risk of PE was also observed in patients with COPD, obesity, lower limb asymmetry and systemic lupus erythematosus.4 Additional risk factors include severe heart failure, recent immobilisation, history of VTE, right ventricular dysfunction and recent invasive procedures or hospitalisation.17
In the current study the majority of patients were anticoagulated for less than 6 months with a median duration of anticoagulation of 90 days. Short-term anticoagulation, typically from 3–6 months, is recommended for PE induced by a reversible risk factor or for a first unprovoked isolated distal deep vein thrombosis (DVT). The treatment duration for a first proximal DVT or PE can fluctuate, with some guidelines advising indefinite treatment based on individual risk factors. Extended anticoagulation, lasting beyond 6 months, is beneficial for patients with enduring or progressive risk factors such as cancer, or a second unprovoked proximal DVT or PE.12,13 The extended treatment over 2 years has been shown to reduce recurrence rates without significantly increasing bleeding risks.14 Decisions regarding the duration of anticoagulation should be individualised, taking factors such as sex, clinical presentation, positive D-dimer test after stopping anticoagulation, antiphospholipid antibody presence, low risk of bleeding and patient preference into account. The use of clinical prediction models for recurrent VTE in determining the duration of anticoagulation is not definitive, further emphasising the need for assessing each case individually.14 The current study showed that non-vitamin K antagonist oral anticoagulants were most commonly used. In fact, non-vitamin K antagonist oral anticoagulants are increasingly recommended as the first-choice treatment for acute PE due to their efficacy, safety and ease of use without the need for routine monitoring.15
In the current study, a total of 32 patients (16.7%) who had PE died during the index admission. The overall crude mortality rate for patients with acute PE is approximately 17.4% at 3 months. In-hospital mortality rates have been decreasing over time, going from 8.3% in 1999 to 4.4% in 2010.20 A study from Denmark showed a decrease in both 30-day and 90-day mortality rates between 2004 and 2014.21 Short-term or 30-day mortality rates for patients hospitalised with PE are approximately 8.9% for women and 9.8% for men, though women have a slightly lower adjusted risk.21 The mortality rate for high-risk patients can be as high as 24% compared to 2% for intermediate-risk and 0% for low-risk patients. Despite improvements, long-term mortality rates remain high, with cumulative mortality rates up to 31.6% at 5 years.22 The current study demonstrated a higher rate of mortality because all patients who had PE were included, regardless of whether PE was the admission diagnosis or patients were admitted with different diagnoses and then developed PE as inpatients.
Mortality was more prevalent in the current study among older age, those with higher PESI scores, patients with central venous access and those with autoimmune disease. Previous studies showed that advanced age, especially over 70, increases mortality in PE patients along with comorbid conditions such as cancer, COPD, heart failure and diabetes mellitus.16,18 Surprisingly, the current study found that heart failure seemed to have a protective effect, which may be attributable to the relatively small sample size (only 42 patients with heart failure). PE severity also influences mortality; patients presenting with massive or submissive PE or right ventricular dysfunction are at a higher risk.
The median follow-up period was 52 months. During this time, 14 patients (9.5%) experienced a recurrence of PE, a rate comparable to previously reported 5-year recurrence rates of PE.19 Chronic medical conditions leading to prolonged immobilisation significantly increase the risk of recurrent PE, as does impaired renal function, indicated by a lower estimated glomerular filtration rate.23 Older age and the presence of antiphospholipid antibodies also contribute to an increased risk of recurrence.24
The current study's strengths include its focus on a relatively understudied region, providing essential data on PE recurrence and associated risk factors. The long median follow-up period of 52 months adds robustness to the findings, allowing for a comprehensive assessment of PE recurrence over time. Additionally, the study's exploration of mortality rates and their association with factors such as age, PESI scores and comorbidities offers valuable prognostic insights.
Despite its strengths, the study has several limitations. The relatively small sample size may have constrained the ability to identify specific factors associated with recurrent PE, potentially affecting the generalisability of the findings. The retrospective observational design introduces the possibility of unmeasured confounding factors influencing the results. For instance, challenges in tracking patient adherence to anticoagulation therapy and the inability to conduct a longer duration of follow-up may have impacted the assessment of recurrence rates. Additionally, the study may have missed certain PE cases diagnosed using alternative methods, such as ventilation/perfusion scans, especially in patients with renal impairment or diagnoses based on clinical and echocardiographic evidence in critically ill patients admitted to the ICU. These factors could contribute to an underestimation of PE incidence and affect the study's conclusions.
5. Conclusion
This study provides valuable insights into the recurrence and risk factors associated with PE in a region with limited data on this topic. The study also highlights the prevalence of comorbidities such as hypertension, diabetes and chronic heart failure among PE patients, which are consistent with previous research. Furthermore, the study confirms that reduced mobility, recent hospitalisation and obesity are significant risk factors for PE, aligning with existing literature. A higher in-hospital mortality rate was found in this study and older age, higher PESI scores, central venous access and autoimmune disease are key predictors of mortality.
Authors' Contribution
Maryam Al Riyami: Conceptualization, Data curation, Writing – original draft. Abdullah Al Alawi: Conceptualization, Writing – original draft, Formal analysis and Supervision. Hajar Al Balushi: Data curation. Raya Al Ghafri: Data curation. Hafsa Al Mamari: Data curation. Jamal Al-Aghbari: Conceptualization, Writing – review & editing, Resources, Validation and Supervision.
Ethics Statement
The study was approved by the Medical Research Ethics Committee of the College of Medicine and Health Sciences at Sultan Qaboos University (MREC #2198).
Conflict of Interest
The authors declare no conflicts of interest.
Funding
No funding was received for this study.
Data Availability
Data is available upon reasonable request from the corresponding author.
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Associated Data
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Data Availability Statement
Data is available upon reasonable request from the corresponding author.