Pressure ulcers (PUs) are among the most common chronic ulcers and complications of hospitalization [1, 2]. PU is a localized lesion on the skin or underlying tissue, which often occurs in hospitalized patients due to pressure or friction on areas of the body, especially bony prominences [3]. PUs based on severity can be classified into four stages: redness of the skin (stage 1), loss of epidermis (stage 2), and loss of fat, muscle, and bone (stages 3 and 4) [4]. PUs are often associated with high treatment expenses, a higher length of stay in the hospital, and a higher risk of infection and mortality for the patients [5-8]. Furthermore, PUs can be good indicators of the quality of patient care, as their incidence varies in different hospitals and health centers [9, 10]. These injuries are often a secondary diagnosis rather than the leading cause of hospitalization, and sadly, they are frequently overlooked by carers [11]. Patients hospitalized or confined to a bed or wheelchair are at high risk for PUs due to clinical instability and less mobility [1, 8, 12]. While other examples of contributing factors for PUs are age, comorbidities, length of stay in hospital, malnutrition, smoking, and prolonged mechanical ventilation [13-17]. The risk of death from a patient with a PU is 2 to 6 times higher than a patient with healthy skin [18]. Although the quality of the care provided has improved significantly in many nations in recent years, nevertheless, PUs remains a significant health challenge worldwide [19]. The prevalence of PUs is varied in different regions of the world [8]. In Iran, for instance, the prevalence of PUs is believed to be between 10 and 50% [19]. According to Akhkand and Karimian studies, the prevalence of PUs in intensive care units (ICUs) ranges between 3.6% and 45.7%, although a more recent study indicated that this rate could be as low as 19% [8, 20]. PUs can cause significant pain, increased risk of infection and sepsis, additional surgical procedures, prolongation of length of stay in the hospital, and imposing additional costs on the patient and the health care unit [8]. Patients with PU often suffer from compromised quality of life and emotional wellbeing [21]. On the other hand, the cost of treatment of PU is 2.5 times the cost of its prevention [22]. Hence, it is necessary to identify high-risk patients and related factors while taking appropriate preventive measures in order to prevent the negative clinical and economic outcomes of PUs [1]. Therefore, the present study aimed to assess the prevalence of hospital-acquired PUs and their grades in patients with trauma, comparison of demographic characteristics, clinical features, and clinical outcomes among patients without and with PUs, and mobility and brain damage among patients with PUs at a referral trauma center in the North of Iran.

This study showed that, generally, the prevalence of PU in patients with trauma was 27.6%. Meanwhile, Grade III (35.5%) and grade I (3.5%) wounds had the highest and lowest frequency of PU, respectively. The mean age of patients with PU was higher than patients without PU. The mean hemoglobin level of patients with PU was lower than patients without PU. PU was more common in males than females, smokers compared to non-smokers, with a history of PU, diabetes mellitus, and hypertension. The mean length of stay in the hospital of patients with PU was higher than patients without PU. 74.3% of people with PUs were completely immobile, and 60% had mild brain damage (GCS of 13 to 15). Also, the number of people with severe and moderate brain injury among PUs patients was 15% and 24.7%, respectively. In the present study, PU was observed in 27.6% of patients with trauma. Furthermore, the prevalence of PU varies in previous studies in different countries. The prevalence of PU in Saudi Arabia [24], Greece [25], Spain [7, 26], Turkey [27], Brazil [28, 29], Norway [23], and Iran [30] was 39.3%, 29.6%, 8.1 to 16%, 15.5%, 11 to 13.6%, 14.9%, and 13.4%, respectively. Differences in findings may be caused by the diversity in the features of the study population, data collection processes, inclusion criteria, and various methods of prevention and control of PU in hospitals [1]. Sample heterogeneity may also affect the prevalence of PU and identified risk factors [23]. Consistent with the present study, previous evidence from Norway [23], Iran [31], Saudi Arabia [24], Portugal [32], Greece [7], Brazil [28, 33], and the United States [34], as well as findings from three review studies showed that prolonged length of stay in the hospital was related with an increased risk of PUs [13, 15, 16]. During a prolonged stay in bed, the patient's tissues remain immobile and pressured, which leads to an increased risk of PUs [1]. One study in Iran showed that PUs in cases with muscle paralysis is five times higher than in others. These patients are at a higher risk of PU due to decreased mobility, increased pressure on the underlying tissues, and tissue necrosis [35]. Also, another study in Iran showed that trauma is a significant risk factor for PUs. Because long-term immobility and increased pressure on an area of the body in trauma patients can lead to the development of PUs [31]. Based on the results of this study, age has been identified as one of the risk factors for PU in patients with trauma, which was concordant with previous evidence from Iran [30, 31], Norway [36], Greece [7], Brazil [28], Portugal [32], and the United States [34]. Meanwhile, factors such as decreased mobility, tissue tolerance, skin vessels, and pain perception could also contribute to an increased risk of PU in older people [15, 31]. Nevertheless, two systematic studies have shown that there is inconsistency in the evidence. Factors such as medical complexity, iatrogenic skin lesions, and the presence of underlying disease in older people may affect findings, and lead to varied results [23]. Grade III and IV ulcers had the highest frequency of PU (34.5%), which was consistent with the results of previous evidence from China [37], Belgium [38], Portugal [32], Norway [36], and Iran [20, 31]. Preventive measures taken by hospital staff can reduce PU progression in the first stage, resulting in a lower incidence of grade III and IV wounds [31]. Consistent with the present study results, two studies have also identified smoking as a predisposing factor for patients with PUs [31, 35]. Nicotine in cigarettes prevents the distribution of prostacyclin and causes the capillaries on the skin's surface to contract. Consequentially, the amount of oxidized blood in the tissues is reduced. Also, carbon monoxide and hydrogen cyanide can hinder the healing process of the wound [31]. This study emphasized that diabetic patients are at a higher risk for PU. Previous studies from Iran [31, 35, 39], Norway [36], Greece [7], and a review study [15, 17] have also reported an association between diabetes and PU. Due to the higher prevalence of diabetes in older people, diabetes may be a confounding factor in analyzing the relationship between age and PUs. However, in the current data analysis, both diabetes and older age have been reported as independent risk factors for PUs [23]. Results of this study implicated that there was a significant relationship between hypertension and hemoglobin levels with PUs. People with hypertension and lower hemoglobin levels were more prone to PUs. Consistent with the present study results, previous studies from Iran [40], and India showed a direct correlation between hemoglobin level and PU development in hospitalized patients [41]. Also, two studies [40, 42] showed a direct correlation between hypertension (systolic blood pressure above 130) and PUs [42]. When the risk of developing a PU is established, individual prevention strategies must be implemented. It is recommended that health managers and policymakers develop care and treatment plans with the risk factors associated with PUs in mind. As nurses have a central role in preventing and managing under-pressure areas, they should also be able to identify the risk factors associated with developing PU and take adequate measures to provide appropriate care. Also, based on the components affecting PUs mentioned in this study, software packages for predicting or preventing pressure ulcers can be designed as a PU reduction strategy.

Overall, the prevalence of PU in patients with trauma was 27.6%. Also, risk factors for hospital-acquired PUs included age, smoking, a history of PU, diabetes mellitus, hypertension, mean hemoglobin, and burn grade. The mean length of stay in the hospital for patients with PU was higher than for patients without PU. 74.3% of people with PUs were completely immobile, whilst this figure was only 60% for those who had mild brain damage. Also, the number of people with severe and moderate brain injury among PUs patients was 15% and 24.7%, respectively. Therefore, it is recommended that health managers and policymakers develop care and treatment plans by considering these risk factors.