Length of hospital stay in obese patients

Katie Wilson


Obesity is a current public health issue in New Zealand’s society. The increasing prevalence of patients with obesity combined with an aging population requiring orthopaedic interventions is growing within New Zealand. There is a large financial burden on the healthcare system which is associated with caring for obese patients while in an acute hospital setting. I will investigate the literature surrounding patients with obesity receiving a total hip replacement and their length of hospital stay compared to patients of a healthy weight receiving the same procedure. It is crucial that nursing practice is informed with knowledge based on current literature and evidence. The clinically significant results from this literature review then form a foundation for evidence based nursing which can be integrated into practice and will facilitate clinical decision making.

Clinical Issue

While working on an acute medical ward, I became vastly aware of the complex implications, on many levels, that obesity has on the health service. On the individual level, there are the significant comorbidities that arise directly from obesity. On a larger scale, there is the financial burden and level of expenditure that is associated with caring for obese patients in the acute hospital setting. The difficulties which surround obese patients in their multifaceted care and their length of stay in hospital resonated with me. I was concerned how excessive weight may influence the development of any potential complications, consequently increasing length of stay in the hospital and therefore incurring higher healthcare costs.

I have chosen to focus my research on the population of patients who have obesity.  This health issue is highly applicable to New Zealand’s current health system due to the increasing rates of obesity in this country. Obesity is an increasing public health issue. The Ministry of Health defines obesity as any individual with a BMI greater than 30kg/m2 (2015b). According to the Ministry of Health Annual Update of Key Results for the 2014/15 period, 31% of New Zealander’s aged 15 years and older can be classified as being obese. Obesity is a risk factor for many comorbidities including greater likelihood of osteoarthritis which may require a total hip replacement (Kremers, Visscher, Kremers, Naessens & Lewallen, 2014). Typically, two thirds of total hip replacement surgeries are performed on patients that are over the age of 65 (Crawford & Murray, 1997). This is important to note, as New Zealand’s population is ageing at a rapid rate. The elderly population is increasing and their total share of the population is also increasing (Statistics New Zealand, 2000). It is therefore inevitable that nurses will encounter greater numbers of obese patients that require total hip replacement surgery in New Zealand. This type of surgery for all patients requires an orthopaedic admission to a specialised hospital care unit. The cost to the healthcare service is estimated per patient per day in a New Zealand public hospital at $349.50 (set at the New Zealand Dollar currency rate in 2005). This cost excludes prescribed drugs and diagnostic tests (World Health Organisation, 2016).

Literature Findings

The articles that I have identified as providing the most objective summary to my research question have collective viability through displaying similarities in their study design and methods. The foremost similarity of these studies is that they all demonstrate quantitative research. They can be further classified as being cohort research designs.  The articles by Foote, Panchoo, Blair, & Bannister (2009), Kremers et al. (2014) and Sadr Azodi, Bellocco, Eriksson & Adami (2006) are all observational prospective cohort designs, in which patients with the exposure of interest, in this case their BMI at the time of surgery, were followed forward in time to determine the outcome of their total length of stay in hospital post total hip replacement. Cohort studies are the most applicable and robust type of study for investigating this research question. Individuals cannot be randomised into exposure and comparison groups based on BMI, as this is a logistical barrier. Therefore, cohort studies are the most relevant design for investigating this research question. Based on the hierarchy of evidence and the important point that randomisation is not possible for this scenario, the studies by Foote et al. (2009), Kremers et al. (2014) and Sadr Azodi et al.  (2006) can therefore be said to have hierarchal strength (DiCenso, Guyatt & Ciliska, 2005).

The studies by Foote et al. (2009), Kremers et al. (2014) and Sadr Azodi et al.  (2006) all present their findings from a large population based patient group. The Kremers et al. (2014) study followed their population group of 8973 patients, of who had either undergone a primary total hip replacement or a revision total hip replacement. This population cohort was sourced from a large United States of America (USA) medical centre, where the hip replacement surgery took place.  Sadr Azodi et al.  (2006) also had a large population cohort of 3309 male patients sourced from the Swedish Inpatient Register. The Foote et al. (2009) population group consisted of 675 patients from South West Britain who underwent primary total hip replacements. The large population based patient groups in these three studies are important to recognise as they reflect the patients that are seen in the acute hospital setting in New Zealand and our population profile. The Organisation for Economic Co-operation and Development (OECD) provides health statistics on obesity rates by country. When comparing the obesity statistics of the USA, United Kingdom and Sweden where these studies were undertaken with the obesity statistics of New Zealand, similarities can be seen. 35.3% of the USA population over the age of 15 are classified as obese, with New Zealand’s statistic similar sitting on 30.6%. The United Kingdom has a lower obesity rate of 24.9%, and Sweden less on 11.7% (Statistics New Zealand, 2015). The close proximity of New Zealand’s obesity rate and the USA’s rate is interesting to note and can be partly explained by the commonalties between the indigenous populations of both countries. Both Maori and American Indians/Alaska Natives experience significant health disparities and therefore poorer health outcomes such as obesity (Bramley, Hebert, Tuzzio & Chassin, 2005).  

Foote et al. (2009), Kremers et al. (2014) and Sadr Azodi et al.  (2006) all utilise the World Health Organisation’s central and universal scaling tool of BMI to classify their study participants into groups based on height and weight (World Health Organisation, 2006).  This similarity in study methodology gives these research articles heightened validity and applicability to answering my initial research question, as it ensures data is all grouped in the same manner. There is some debate as to if BMI is an appropriate indicator for classifying an individual into a weight category, as it does not distinguish between the differences in weight associated with fat and weight associated with muscle (Balentine et al., 2010). However, BMI is a useful tool which is able to be utilised to describe population based levels of weight. It also provides an indication of an individual’s increased risk of health conditions that are commonly associated with obesity (Ministry of Health, 2016).

Kremers et al. (2014) has actively worked to eliminate potential confounding factors that could influence the outcome of interest in their study. The lack of randomisation in this study showed that the outcome of length of hospital stay could have arisen due to differences in baseline characteristics of the exposure and comparison groups, also known as confounding factors (DiCenso et al., 2005). Investigators attempted to minimise these confounding factors by restricting the population group to individuals that did not present with comorbidities that are knowingly associated with an increased length of stay in hospital. This indicated that any patient who presented with obesity related conditions such as congestive heart failure, valvular diseases, diabetes, renal failure, liver disease or fluid and electrolyte disorders were immediately excluded from participating in the study (Kremers et al., 2014). In comparison to this study, Foote et al. (2009) and Sadr Azodi et al.  (2006) did not actively eliminate patients with known comorbidities, as their studies had multivariable components to them, in which researchers looked at multiple factors that can influence an individual’s length of stay in hospital following total hip replacement. Therefore, recognition needs to be given to this as the lack of exclusion of patients with obesity related comorbidities may have altered the final results.

Most importantly, Foote et al. (2009), Kremers et al. (2014) and Sadr Azodi et al.  (2006) all concluded similar results in their studies.  They were all able to form the conclusion that BMIs that sit outside of the normal parameters are significantly associated with longer hospital stays following total hip replacement. Foote et al. (2009) concluded that morbidly obese patients with a BMI greater than 35kg/m2 had the greatest length of stay post-surgery, with a median stay of 11.5 days. This can be compared to participants with BMIs ranging between 18.5kg/m2 and 34.9kg/m2, who had a median stay of 8 days. Twice as many morbidly obese patients stayed more than 2 weeks when compared to participants classed as obese/normal with BMIs less than 34kg/m2. Sadr Azodi et al.  (2006) also confirmed that increasing BMI lead to an increased mean length of hospital stay. However, they found that patients with a normal weighted BMI had a median stay of 9 days and patients with an obese BMI of greater than 30kg/m2 had a median stay of 10days.   Kremers et al. (2014) found that hospital stays were longest for patients at extreme ends of the BMI spectrum.  This can additionally be supported by a study completed by Zizza, Herring, Stevens & Popkin who state that “extreme values of BMI, underweight and obesity, exhibited greater lengths of stays while normal-weight exhibited the shortest length of stay” (2004, p.1589). 

Implications for Practice

The foremost prominent implication that can be formulated from the research findings for nursing practice surrounds the economic burden of the obese patient on the healthcare system. Healthcare budgets are finite and healthcare organisations naturally seek to shorten the length of hospital stay, without compromising patient care (Foote et al., 2009).  It is evident from the above literature findings that obese patients with BMI’s greater than 35kg/m2 have longer length of hospital stays compared to individuals within the normal BMI scale range.  This can be explained by the increased surgical risk for post-operative complications such as site infection, myocardial infarction and peripheral neuropathy that patients with obesity experience (Lebuffe et al., 2010). The Kremers et al. (2014) study states that with every 5-unit increase in BMI above 30kg/m2, an increased cost of USD $744 can be associated with this patient’s care and therefore post-operative length of stay. Relating this to a New Zealand context, in 2006 it is estimated that $686,000,000 from the New Zealand Government’s healthcare budget was spent on costs directly attributable to obesity (Lal, Moodie, Ashton, Siahpush & Swinburn, 2012). The cost of obesity related complications both on the smaller scale of length of stay in hospital post total hip replacement and the wider scale of the burden of the multiple comorbidities associated with obesity in New Zealand are growing.

The growing population of obese patients in New Zealand (Ministry of Health, 2015b) means that nurses will need to become increasingly aware of the unique requirements that exist when caring for these patients. The basic care of patients living with obesity can pose difficulty to nursing staff. Examples of difficulties in the clinical setting include inadequate fitting equipment such as mobility aids, blood pressure cuffs and hospital gowns, extra assistance and staffing required to aid in the completion of activities of daily living (ADL) and inadequate bed and chair sizes (Taggart, Mincer & Thompson, 2004). Nurses need to have knowledge and training surrounding safe and effective moving and the handling of the bariatric client. These clients can be more time consuming for nursing staff, as additional support staff are required for transferring and moving the client. Equipment must also be specific to accommodate the safe working load to meet patient needs, such as bariatric chairs, pressure reduction mattresses and appropriate slings and hoists (ACC, 2012).

Awareness of the comorbidities that often accompany obese patients has been an important theme in the research literature. Comorbidities such as diabetes and valvular diseases often present in the obese patient (Kremers et al., 2014). Nurse’s awareness of the heightened risk to post-operative complications, due to the presence of obesity related comorbidities. For example, following total hip replacement, nurses should assess, record and report any variance of abnormalities from baseline characteristics of the patient. Changes could indicate early onset of complications, for example wound dehiscence (Doyle, Lysaght & Reynolds, 2009). If nurses are able to detect early warning signs of complications, interventions can be implemented to change the outcome of hospital stay discharge times, which will decrease financial costs.


Further research into the topic of obesity is highly recommended.  This population is unique and has its own multi variable needs and risks. Further research is required to best target and manage the needs and complications which will inform the decision making outcomes and practice for these vulnerable health consumers. As a large proportion of the population has obesity, the continuing research regarding this issue is important.   

The obesity epidemic in New Zealand is a growing issue. Education and health literacy of the general public is vital. This should be targeted at a societal level while also taking into account the significant inequities associated with obesity and focus put on those populations that are disproportionately burdened by it (New Zealand Medical Association, n.d.).

Recommendations from the research include the importance of clinicians advising weight loss to obese patients prior to any major surgery. Zizza et al. (2004) state that “the treatment and prevention of obesity will reduce use of hospital care and subsequent health care costs associated with the obesity epidemic”. Therefore, if clinicians are able to educate on weight reduction prior to surgery through empowerment, not only will the physical and mental wellbeing of the individual improve, their hospital length of stay will be reduced, therefore decreasing health care costs.

In conclusion, using the framework of a literature review to answer my research question, the evidence that has been examined and analysed has informed my knowledge and consequently influenced my clinical practice. The findings of the research articles clearly identify that patients with obesity having a total hip replacement in a specialised hospital care unit have an increased length of hospital stay. My recommendations suggest that further research is vital to reduce complications and to improve the outcomes of stay for this vulnerable population.


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