According to our study, the cumulative five-year mortality of arthroplasty group and conservative treatment group is 51.5% and 79.2%, respectively. The femoral neck fracture patients age over ninety can benefit from arthroplasty surgery. Our study suggested that patients receive conservative treatment had higher rates of short and long-term mortality compared with that performed surgery. They also had a shorter mean survival time compared with arthroplasty patients. Also, the annual mortality of arthroplasty group is significantly lower than the conservative treatment. To our knowledge, the current study is the first to assess this critical issue in a low-income or middle-income country, and timeline spans more than sixteen years in the world.
The chance of surviving to the age of 90 has increased markedly over the last 50 years in high-income countries[21]. The life expectancy for 90-year-olds (ranging 4 - 5 years) is still reasonably short than that for an 80-year-old (ranging 8 -10 years) [10,11,21,22]. Recently, two successive cohorts study from China also present consistent with the results of these developed countries [23,24]. Liu et al. demonstrated that the life expectancy of the population ages 90–99 was 3.9-4.0 years [23].
On the other hand, there is a lack of consensus on the definition of long-term survival for hip fracture patients age 90 and older. However, recent studies demonstrated that the mortality rates of nonagenarian hip fracture patients would return to an equivalent mortality risk to the average population at five years after injury [9,12-16]. Furthermore, less than 5% of patients can survive for more than ten years[16]. Consequently, the five-year survival rate can be considered as a reliable parameter to reflect the long-term outcomes of patients in the extremely elderly suffered hip fractures.
During the several decades, the dilemma of how to optimal care the extremely elderly hip fracture patients included two aspects. First, previous reports about hip fracture patients age above 90s mainly focused on the 30-day and 1-year mortality, paid less attention to the survival status for more than two years. Secondly, many studies have previously evaluated the long-term mortality among hip fractures, but only a few have assessed the survival of the nonagenarians fracture patients[9, 11,17, 25, 26].
Compared to other investigations into short-term mortality after surgery for hip fracture, our 30-day rates were similar (9.1% versus a range from 5.6 to 9.6%) with the previously reported [6,10,11,17,27,28]. An exception of a Taiwan investigation in which 95.4% survived to 30 days, which is the lowest mortality of nonagenarian femoral neck fracture patients in literature[16]. However, there are some researches revealed conflict results with this current study, which the 30-day mortality higher than 10%[7,26,29]. This gap may be partially due to different social and cultural aspects, policy, and Health System services. Advances in medications, lifestyle, and socioeconomics might also contribute to this mixed survival outcomes.
Based on national data from the Chinese Longitudinal Healthy Longevity Study, 7234 individuals who survive to age 90 years have an all-cause annual death rate of 22.4-23.4%[24]. An earlier published study identified that the expected 1-year survival rate for the average Japanese population aged 90 years and older was 83.7% for women and 77.6% for men[30]. In our study, the 1-year mortality rate of the arthroplasty group and conservative group was 12.1 % and 43.4%, respectively. One of the possible reasons for this difference is the surgical treatment of the femoral neck fracture no longer increasing the mortality compared with the general population during the last two decades[31].
Our 1-year mortality result is also consistent with another study performed in North China. In this multicenter retrospective study of 327 nonagenarian individuals, Liu et al. showed the 1-year mortality after surgery is 11.6%[32]. Previously studies demonstrated that the 1-year mortality for nonagenarian femoral neck patients varied range from 23.3% to 47.6%[6,16,30, 33-35]. Although our result of 1-year mortality of arthroplasty group was lower than previously mentioned studies, similar to other studies [11,36-38], another possible explanation for the difference of mortality rate between this study and previous studies might be related to different demographics including age, distribution of gender, and comorbidity in each study.
There are limited studies that demonstrated that the five-year mortality of hip fracture patients varied from 55% to 82%[11,16,17,26]. After retrospective analysis of a total of 149 patients, de Leur et al. found that the five-year survival of nonagenarian hip fracture patients is 18% after osteosynthesis[17]. In a large nationwide database study of 11,184 nonagenarian patients undergoing surgery for hip fracture in Taiwan, the mortality rates increased from 29.5% at 1-year to 78.1% at 5-years [16]. Lin et al. also demonstrated that 10-year mortality is 95.90%, which means less than 5% of patients can survive more than ten years[16]. The five-year mortality (51.5%) of the arthroplasty group in this study is consistent with the result of Gregory et al. (55%) and Knauf et al. (61.5%) [11,25], but higher than previously mentioned the two studies.
The survival time of the arthroplasty group is significantly higher than the conservative group (53 months versus 22 months, P=0.001). This gap of survival time may be a result of highly selective patient recruitment in that series, resulting in only 33 nonagenarians operated on over 16 years. Larger sample size and multicenter study deserve to comprehensive evaluate and get a more explicit scene of long-term survival among these patients.
In our study, we found a higher 5-year survival probability in the arthroplasty group patients (39.3% vs. 11.3%, p=0.002277). Manton et al. showed that the five-year survival probability of Japan age at 90 is range from 22.7 to 33.0%[39]. In the Netherlands, the survival rate of people age 90s increased from 19.45% of 1990 to 31.4% of 2016[40]. Comparing with the observed survival probability for patients in the current study, the survival rate among the conservative group (11.3%) was less than those of average population data, and the result of the arthroplasty group (39.3%) is similar with these average population. Although the sample size is limited, the result can partially reflect the advantage of surgery for long-term survival among this unique group patients. This encouraging result can contribute to the fast rise in healthcare expenditure infrastructural development and the recent implementation of universal healthcare coverage in China [24,41].
The primary strength of this study was the data collection, low rate of lost follow-up (<3%) and the duration of follow-up, which more than ten years, is the longest of any published series and exceeds the life expectancy for this age group. This cohort spanned more than ten years, which eliminated the bias effects of demographic change. To the authors’ knowledge, this is the most extensive study to date comparing the conservative treatment and arthroplasty in patients with femoral neck fracture age over ninety.
The findings from our study must be comprehensively considered the limitations of our study design. The limitations of our study have inherent to the nature of retrospective review performed in a single teaching hospital. The inclusion of institutionalized patients could add heterogeneity to the study. Future longitudinal and multi-center studies should be the optimal research design to establish practice guidelines for the treatment of femoral neck fractures in extremely elderly. Second, as the hospital medical record system provides only inpatient information, pre-hospitalization and post-discharge functional outcomes were not available for analysis. The further prospective, longitudinal studies should assess the influence of these factors on the outcome of the patient. Finally, because this study did not include intertrochanteric fractures, so our conclusions are not representative of all nonagenarian and centenarian hip fractures.