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Incidence and Prevalence

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Pressure injuries, is the term used in the current document, to acknowledge that pressure related tissue damage includes stages of harm before an ulcer is visible.  Pressure injures have also been called pressure ulcers, decubitus ulcers, ischemic ulcers, pressure sores, bed sores or skin sores, have been defined as a “localized injury to the skin and/or underlying tissue usually over a bony prominence as a result of pressure or pressure in combination with shear and/or friction. A number of contributing or confounding factors are also associated with pressure injuries; the significance of these factors is yet to be elucidated.” (National Pressure Injury Advisory Panel 2007). The NPIAP (2019) identify that the primary cause of pressure injuries is felt to be externally applied pressure over bony prominences such as the sacrum and ischial tuberosities (IT), for a prolonged period of time. Because pressure can be exerted while the body is in different positions, the term “decubitus” is no longer commonly used to describe pressure injuries as it refers only to pressure injuries acquired while “lying down.” Applied pressure leads to decreased blood supply to the overlying soft tissues (i.e., tissue ischemia) and can ultimately cause tissue necrosis (Lamid & Ghatit 1983; Crenshaw & Vistnes 1989; Bogie et al. 1995). DeLisa and Mikulic (1985) have noted that “the visible ulcer represents only the tip of the iceberg or the apex of the lesion” (p. 210). Erba et al. (2010), using 3 dimensional analyses of silicone moulds, confirmed the pyramidal shape of stage IV ischial ulcers in all 10 paraplegic patients included in their study. Deeper tissues, such as muscle, are more sensitive than skin to ischemia caused by pressure (Daniel et al. 1981; Nolan and Vistnes 1980). Deep tissue injuries have been added as a distinct pressure injury in the National Pressure Injury Advisory Panel’s 2019 updated pressure injury staging system (Black et al. 2007).

Table 1 reflects the various ways that pressure injury incidence and prevalence is reported: by grade, by location, in paraplegia versus tetraplegia, in people with SCI from traumatic or non-traumatic origin, by time since injury and by jurisdiction (e.g., health-care setting vs. living in community or by geographic region).

Table: Incidence and Prevalence of Pressure Injuries Post SCI

Discussion

Annual prevalence rate reports range from 10.2% to 38% (DeLisa & Mikulic 1985; Byrne & Salzberg 1996; Walters et al. 2002). Chen et al. (2005) reported an increasing pressure injury prevalence in recent years not explained by aging, years since injury or varying demographics. Risk of pressure injuries was steady for the first 10 years and increased 15 years post injury. Fuhrer et al. (1993) noted that less severe pressure injuries (stages I and II) comprised about 75% of the total number of ulcers observed, with the 25% as more severe (stage III and IV).

When reported overall (no breakdown by grade, location), incidence rates as high as 71.8% have been published (Taghipoor et al. 2009), although these reflect biases in the study population associated with participants limited to having low income, and motor- and sensory-complete injuries. In an Iranian study, overall incidence rates of pressure injuries were reported as 28.2% in patients with non-traumatic SCI and 71.8% in those with SCI secondary to traumatic etiology (Taghipoor et al, 2009). The highest incidence by grade of severity is grade II (Raghaven et al. 2003) and the most common pressure injury site is the sacrum (Nogueria et al. 2006; Raghaven et al. 2003; Chen et al. 1999). Anson and Shepherd (1996) inferred that continuous prevention diligence (e.g., patient education, follow-up and extended medical care) may decline after 15 years post-injury as reflected by the simultaneous increase in grade III and IV ulcers (11-15 yr=16%; >15 yr=31.6%) and decrease in grade I and II ulcers (11-15 yr=94%; >15 yr=68.4%).

Although the United States Model Systems report a peak in rehospitalization as a result of pressure injuries at five years post-discharge from initial rehabilitation (Cardenas et al. 2004), pressure injuries were still one of the most common secondary complications at annual follow-ups (McKinley et al, 1999). Prevalence continued to increase up to 20 years post-injury for individuals with a complete injury. Prevalence for those with an incomplete injury peaked at 15 years post-injury and decreased from there when seen at 20 year follow-up. Not surprisingly, pressure injury prevalence was highest in individuals with a complete versus incomplete injury (McKinley et al. 1999). Prevalence continued to increase in both groups over time until 15 years post-injury. Fortunately, people with incomplete injuries saw a slight decrease in prevalence on 20 year follow-up. The difference in prevalence rates was further amplified between those with paraplegia versus tetraplegia, with the latter being more heavily plagued with pressure injuries in general. However, those with either complete paraplegia or tetraplegia continued to reflect increasing pressure injury prevalence at the 20-year follow-up.

When a pressure injury is severe and not treated aggressively it can lead to further disability (e.g., reduced mobility, dependence, surgical intervention, amputation, fatal infection; Krause 1998). It has been estimated that 7-8% of those who develop pressure injuries will die from related complications (Richards et al. 2004). Due to the increasing life expectancy for those who sustain an SCI, the risk of developing pressure injuries is even greater; thus, recognition of risk factors and pressure injury prevention is a priority and daily concern for both individuals with SCI and health care providers.