Despite the higher prevalence of comorbidities in the elderly, the proportion of PN-related complications such as hypoglycaemia, hyperglycemia, CRBSI and fluid overload were similar between two groups. There were no significant differences in total mortality between the younger and elderly patients on PN, even when a higher age cut-off of 80 years was used. A subgroup analysis was performed for patients with and without a cancer diagnosis, which also found no difference in total mortality between younger and elderly patients, at both age 65 and 80 cut-offs. Based on univariate analysis performed, when considering major comorbidities and age, the only correlating factor for mortality for patients with acute intestinal failure was that of presence of cancer and a higher Karnofsky score .
Our findings suggest that in the presence appropriate clinical indications with close monitoring and adjustment of PN by a dedicated nutrition support team, PN-related complications were not different between the elderly and the younger patient demonstrating that PN in the elderly can be safe and age should not be a discriminator towards the initiation of PN. Similar findings were observed in a large regional wide audit conducted in North of England where the median age of patients was 6512. The findings further justify the need for dedicated nutrition support teams who are able to advocate for the appropriate use of PN and closely monitor complications of nutritional support therapy13,14.
Even though the total calories, dextrose and protein received were lower in the elderly group, the proportion of patients that achieved their target calories and the number of days taken to achieve target calorie were the same for both groups. Whilst indirect calorimetry is seen as the clinical “gold standard” for caloric estimation, it remains impractical for daily use. The Mifflin St Jeor which has been shown to be the closest predictive equation in performance to indirect calorimetry is what we employ in our centre to estimate target calories15. It is expected that the basal metabolic rate decreases with age16 and it is therefore not unexpected that the total calorie and macronutrient requirements dictated by formulas such as the Mifflin St Jeor are lower in the elderly grou15. The average total calorie received was 20.8 (± 7.8) kcal/kg/day and the average total protein received was 1.1 (± 0.4) g/kg/day in the elderly group. These are within the acceptable ranges recommended by major guidelines bodies17,18.
We demonstrated similar rates of hypoglycaemia and hyperglycemia in both elderly and young patients, despite a higher prevalence of diabetes in the elderly group. Our local practice is to aim to reach target calories in 3–5 days, and to start at less than 40% of target calories for patients who are at high risk of refeeding. For the first 3 days, each patient has repeated electrolytes, and their capillary blood glucose monitored closely with any aberrations corrected and considered before an increase in calories is considered. Good glycemic control is important as it has been shown that hypergylcemia is a predictor of mortality and infection while receiving PN19 .
Surprisingly, our study found that the mean length of stay was shorter in the elderly patients as compared to the younger patients. This could be due to the fact that younger patients requiring PN were likely to have a more complex and aggressive course of disease and treatment that requires a prolonged hospital stay. When we delved further in the younger cohort, 21 of the younger patients had hospital stay exceeding 90 days, the longest being up to 330 days. On the other hand, only 4 of elderly patients had hospital stay exceeding 90 days, the longest being 108 days. When these group of patients whose stay exceeded 90 days were excluded, the mean length of stay was similar between both groups.
Whilst inpatient mortality is an infrequent event in our cohort, the cumulative survival was comparable between the two groups even at higher cut off of 80 years of age and amongst elderly vs young patients with or without cancer. It appears that the age-related increase in cancer mortality decelerates with age20–22. Though it is unclear what contributes to such a paradoxical phenomenon, experts speculate that it could be an issue of survivor bias, whereby individuals who have been exposed to fewer risk factors surpass the age of individual who were exposed or due to variations in the diagnostic screening or testing in the elderly21,23. Of note in our univariate analysis, a Karnofsky score > 80 instead of age is a risk factor of inpatient and overall mortality which suggest that performance status is a more important factor in determining mortality instead of age amongst patients with acute IF who might require short term PN.
We believe our study is novel in describing and comparing the characteristics of elderly patients with acute intestinal failure receiving PN in the acute hospital setting and comparing PN-related complications and clinical outcomes against young patients. While type I intestinal failure is usually short term and self-limiting, type II intestinal failure is a prolonged acute condition in metabolically unstable patients requiring complex multi-disciplinary care and requiring PN over weeks or months, with a cut off PN use of ≥28 days described in the literature29. In our cohort, there were more younger patients who had type II intestinal failure ( 20.4% vs 10.6%, p < 0.05) contributing to the longer duration length of stay in the younger group. Despite volatile metabolic and physiologic changes in response to acute stress sustained in acute illness ,our study findings were reassuring that elderly patients experienced similar complications at a comparable rate with young patients. Similar findings had been reported in the elderly who received home PN in the community setting for which acute illness would have been stabilised and managed before continuing PN in the community9 − 11.
Our study has a few limitations. Firstly, our study is conducted in a single-centre tertiary care hospital with a dedicated nutrition support team which may not make the study findings generalizable to other centres without dedicated nutrition support team. In addition, due to retrospective analysis of data collected as part of prospective cohort study, the associations are not proof of causality. Also, we could not obtain the extent of disease and treatment that patients received which may explain the longer length of stay in the younger patients. Regardless, we managed to capture information that is pertinent to PN-related complications in both groups which suggest that the elderly fare as well as the younger patients.
In conclusion, our study supports the use of PN in the elderly. With a growing population of the elderly worldwide and an increasing proportion of elderly patients admitted to hospitals requiring PN, there is a need for stringent protocols that caters to the multiple co-morbidities in this group of patients. The margin of error that is allowed in the elderly is much smaller as they are less likely to tolerate complications due to multiples co-morbidities and having poorer reserves and functional status. This further underscore the need for dedicate nutrition support teams who are able to closely track and address electrolyte disturbances, hypo/hyperglycemia events and the fluid status whilst making adjustments to the PN prescription to ensure safe delivery of PN.