Hip fractures in an aging population : clinical and epidemiological aspects

Hip fracture, a fracture of the proximal femur is a common and serious injury that mostly affects older people. Almost all hip fractures are treated surgically and optimizing perioperative and operative care is important to allow the patients the best possible chance of continued life and, ideally, good health and independence.

The purpose of this thesis is to fill some of the knowledge gaps regarding patients with hip fracture: to explore the association between time to hip fracture surgery and death, as well as other adverse outcomes, to compare two surgical methods for trochanteric hip fracture in a context where a newer method is continually winning ground from an older, to describe regional differences in hip fracture incidence in Sweden and to explore some explanatory factors as to why there are regional differences.

Study I was a retrospective, nationwide cohort study using prospectively collected data from the Swedish Hip Fracture Register RIKSHÖFT (SHR). The study explored the association between time from hospital arrival to start of hip fracture surgery (<24 hours vs >24 hours) and death within 4 months of surgery. We included 59,675 patients and found that longer time to surgery was associated with increased mortality, primarily for women. When stratifying the analyses by American Society of Anesthesiologists (ASA) classification, a statistically significant association between longer time to surgery and death remained among the sickest patient (ASA classification 3 and 4) only.

Study II was a retrospective, nationwide cohort study using data from SHR, the Swedish National Patient Register (NPR), the Swedish Cause of Death Register (CDR) and the Swedish National Prescribed Drug Register PDR. The study explored the association between time to hip fracture surgery (divided into <12 hours, 12-24 hours and >24 hours, with <12 hours as the reference group) and postoperative morbidity, specifically atrial fibrillation/flutter (AF), congestive heart failure (CHF), pneumonia and "acute ischemia" (a combination of the diagnoses for stroke/intracranial bleeding, myocardial infarction and acute kidney injury). The outcome diagnoses used were registered after index hospitalization discharge until 120 days later. We also described time spent in hospital from hospital discharge until 120 days thereafter for the three "wait time groups". 63,998 patients were included, and there were statistically significant associations between waiting >24 hours for hip fracture surgery and having AF, CHF and "acute ischemia". Stratification by ASA classification revealed that these associations were present only in patients with ASA 3-4.

Study III was a retrospective, nationwide cohort study using data from SHR, NPR and the Swedish Dwelling Register. The study explored the association between surgical method for trochanteric hip fracture (Sliding Hip Screw (SHS) vs Intramedullary Nail (IMN)) and death within 120 days after surgery; as well as between surgical method and return to independent living among a sub-set of patients living independently at baseline. 27,530 patients were included in the study, and 12,041 of them were investigated for the outcome return to independent living. There were no overall differences in death within 120 days or return to independent living between SHS and IMN. IMN was associated with lower return to independent living among men and younger (70-84 years) patients with two-fragmented fractures, but these results need to be interpreted with caution due to substantial loss to follow-up.

Study IV was a retrospective, nationwide cohort study using data from the Swedish Total Population Register (TPR), NPR, PDR, The Longitudinal Integration Database for Health Insurances and Labour Market Studies (LISA) and The National Register of Care and Social Services for the Elderly and Persons with Impairments (SSR). The study explored regional differences in first hip fracture incidence in Sweden, differences between the yearly quarters and whether potential explanatory factors eliminated the differences in incidence between counties. 2,879,444 individuals were included in the study. Sex-and county specific crude and age standardized incidence rates were calculated, revealing regional differences with higher incidence rates in the north of the country. The summer half of the year had lower incidence rates overall. Differences between counties persisted despite adjustments for several potential explanatory factors.

Conclusions: Waiting >24 hours for hip fracture surgery was associated with increased 4 month-mortality and increased postoperative morbidity within 120 days after index hospital discharge. There were no differences in death at 120 days after surgery when comparing SHS and IMN for trochanteric fracture. Subgroups of patients with two-fragmented fracture had lower return to independent living when operated with IMN, but the results must be interpreted with caution. There were regional differences in first hip fracture incidence that cannot be explained by differences in the factors investigated in our study.

List of scientific papers

I. Greve K, Modig K, Talback M, Bartha E, Hedstrom M. No association between waiting time to surgery and mortality for healthier patients with hip fracture: a nationwide Swedish cohort of 59,675 patients. Acta Orthop. 2020;91(4):396-400. https://doi.org/10.1080/17453674.2020.1754645

II. Greve K, Ek S, Bartha E, Modig K, Hedstrom M. Waiting more than 24 hours for hip fracture surgery is associated with increased risk of adverse outcomes for sicker patients: a nationwide cohort study of 63,998 patients using the Swedish Hip Fracture Register. Acta Orthop. 2023;94:87- 96. https://doi.org/10.2340/17453674.2023.9595

III. Greve K, Ek S, Bartha E, Modig K, Hedström M. Sliding hip screw versus intramedullary nail for trochanteric hip fracture regarding death within 120 days and ability to return to independent living. Bone & Joint Open. 2024;5(10):843-50. https://doi.org/10.1302/2633-1462.510.BJO-2024-0028.R1

IV. Greve, K, Ek, S, Bartha E, Sääf M, Hedström M, Modig, K. Regional differences in hip fracture incidence in Sweden. [Manuscript]