In the present study, we found that thirty-three (66%) patients were hospitalized for more than 14 days. An extended LOS was significantly associated with the occurrence of pneumonia after surgery (OR, 8.95) and the mean diastolic blood pressure during surgery (OR, 0.86) but not the anaesthesia technique. The mean diastolic blood pressure of patients who were hospitalized for no more than 14 days in our study was 71.7 mmHg, while it was 63.9 mmHg in patients who were hospitalized for more than 14 days.
Pneumonia, one type of HAI, accounts for a large proportion of the problems caused by health care and is associated with an extended LOS. A meta-analysis of costs and the LOS attributed to the five major HAIs in the US adult inpatient population at acute care hospitals also showed that postoperative pneumonia resulted in a 13.1-day increase in the LOS [10]. The NLR as an inflammatory marker has been indicated as being associated with pulmonary complications and long-term outcomes in a variety of diseases [11-13]. Ki-Woong and colleagues [12] previously demonstrated that a higher NLR predicted community-acquired pneumonia in patients with acute ischaemic stroke. Another study from China [13] showed that the NLR was a significant risk factor for postoperative pneumonia after meningioma surgery. For geriatric patients undergoing hip fracture surgery, Fisher [11] reported that a high NLR (D0) was a significant risk factor and moderate predictor of a high postoperative inflammatory response/infection. In our cohort, all patients underwent surgical treatment, and the median NLR (D0) value was six. Our study also showed that postoperative pneumonia was significantly associated with the NLR (D0) (OR, 1.20), which may be a predictor of postoperative pneumonia in this setting. The NLR may help identify high-risk patients in a timely manner and provide guidance for further studies about preventive antibiotic therapy.
In addition, we found that compared with the use of general anaesthesia, the use of regional anaesthesia was not associated with a lower incidence of postoperative pneumonia or a shorter LOS. The results do not support an LOS benefit of regional anaesthesia compared with general anaesthesia in patients aged 90 years and over. However, it is important to note that most of the very elderly patients in our study received regional anaesthesia (76%). This is in line with the general trend of the guidelines and literature [4-7] requirements for hip joint surgery in elderly patients. Some studies [14, 15] suggest that compared with general anaesthesia, regional anaesthesia reduces the incidence of postoperative adverse outcomes. While we cannot deny that regional anaesthesia may be beneficial in older hip fracture surgery patients, the conclusions of these studies or guidelines are generally based on older patients over the age of 65. It is questionable whether these findings are applicable to elderly patients over 90 years old. Advanced age (over 90 years) itself is a major risk factor for poor prognosis. In our study, the proportion of patients undergoing regional anaesthesia was approximately the same (74.2% vs 78.9%) in the pneumonia group as in the non-pneumonia group, with no significant difference. Although regional anaesthesia may stabilize haemodynamics in older hip surgery patients, the target blood pressure values are still of more concern.
Perioperative hypotension is associated with an increase in postoperative morbidity and extended LOS. Individualized blood pressure management strategies could reduce the risk of postoperative pneumonia among high-risk patients undergoing major surgery [16]. However, for patients over 90 years of age undergoing hip surgery, there is no recognized blood pressure index and specific threshold. Our research found that the mean diastolic blood pressure rather than the mean arterial pressure was another risk factor for extended LOS. One previous study [17] noted that in the elderly population, a diastolic blood pressure reduction below 70 mmHg should be avoided because it is associated with increased mortality. A possible explanation for this phenomenon could be an imbalance between sufficient perfusion pressure and arteriolar vasodilation, both of which are required for adequate tissue perfusion [18]. Impaired microcirculation, especially in the coronary bed, may account for increased mortality and extended LOS. Anaesthesia can be seen as another antihypertensive method, and perhaps we should keep the mean diastolic blood pressure above 70 mmHg in geriatric patients during surgery to shorten the LOS.
There are several limitations to be addressed. First, it must be mentioned that the conclusions of our study are surely limited by the comparatively small sample of patients, which only results in information on a very specific and small cohort. We could not analyse the risk factors for in-hospital mortality because of the relatively small number of events (2 deaths in 50 patients). Second, the study was only observational and occurred in one hospital unit with a short observation period, which only included the in-hospital period. The information regarding patient symptoms relied solely on the input of information by the treating doctors into the medical database, although we expect any related errors or omissions to be evenly distributed. Third, we did not take the elapsed time from hospital arrival to surgery into consideration, but this time is regarded as an important risk factor for extended LOS and 30-day mortality. All patients in the cohort waited more than 24 hours to undergo surgery. The 2 main reasons for this delay were preoperative medical clearance and operating room access. Fourth, in the univariate and multivariate analyses, multiple comparisons and statistical tests were conducted. However, considering the small sample size in our analysis, we did not use any correction for the type I error, which may have led to false positive findings. The results from the models should be regarded as hypothesis-generating rather than as solid evidence of the risk factors for extended LOS.
In conclusion, complications after hip fracture surgery are common in geriatric patients. A lower mean diastolic blood pressure during surgery and the occurrence of postoperative pneumonia may extend the LOS. The use of regional anaesthesia compared with general anaesthesia was associated with neither a lower incidence of postoperative pneumonia nor a shorter LOS.