Post-acute pathways among hip fracture patients: a system-level analysis

Abstract Background Hip fractures among older adults are one of the leading causes of hospitalization and result in significant morbidity, mortality, and health care use. Guidelines suggest that rehabilitation after surgery is imperative to return patients to pre-morbid function. However, post-acute care (which encompasses rehabilitation) is currently delivered in a multitude of settings, and there is a lack of evidence with regards to which hip fracture patients should use which post-acute settings. The purpose of this study is to describe hip fracture patient characteristics and the most common post-acute pathways within a 1-year episode of care, and to examine how these vary regionally within a health system. Methods This study took place in the province of Ontario, Canada, which has 14 health regions and universal health coverage for all residents. Administrative health databases were used for analyses. Community-dwelling patients aged 66 and over admitted to an acute care hospital for hip fracture between April 2008 and March 2013 were identified. Patients’ post-acute destinations within each region were retrieved by linking patients’ records within various institutional databases using a unique encoded identifier. Post-acute pathways were then characterized by determining when each patient went to each post-acute destination within one year post-discharge from acute care. Differences in patient characteristics between regions were detected using standardized differences and p-values. Results Thirty-six thousand twenty nine hip fracture patients were included. The study cohort was 71.9 % female with a mean age of 82.9 (±7.5SD). There was significant variation between regions with respect to the immediate post-acute discharge destination: four regions discharged a substantially higher proportion of their patients to inpatient rehabilitation compared to all others. However, the majority of patient characteristics between those four regions and all other regions did not significantly differ. There were 49 unique post-acute pathways taken by patients, with the largest proportion of patients admitted to either community-based or short-term institutionalized rehabilitation, regardless of region. Conclusions The observation that similar hip fracture patients are discharged to different post-acute settings calls into question both the appropriateness of care delivered in the post-acute period and health system expenditures. As policy makers continue to develop performance-based funding models to increase accountability of institutions in the provision of quality care to hip fracture patients, ensuring patients receive appropriate rehabilitative care is a priority for health system planning

The JNK- and AKT/GSK3β- signaling pathways converge to regulate Puma induction and neuronal apoptosis induced by trophic factor deprivation.

The AKT, GSK3 and JNK family kinases have been implicated in neuronal apoptosis associated with neuronal development and several neurodegenerative conditions. However, the mechanisms by which these kinase pathways regulate apoptosis remain unclear. In this study we have investigated the role of these kinases in neuronal cell death using an established model of trophic factor deprivation induced apoptosis in cerebellar granule neurons. BCL-2 family proteins are known to be central regulators of apoptosis and we have determined that the pro-apoptotic family member Puma is transcriptionally up-regulated in trophic factor deprived neurons and that Puma induction is required for apoptosis in vitro and in vivo. Importantly, we demonstrate that Puma induction is dependent on both JNK activation and AKT inactivation. AKT is known to regulate a number of downstream pathways, however we have determined that PI3K-AKT inactivation induces Puma expression through a GSK3β-dependent mechanism. Finally we demonstrate that the JNK and AKT/GSK3β pathways converge to regulate FoxO3a-mediated transcriptional activation of Puma. In summary we have identified a novel and critical link between the AKT, GSK3β and JNK kinases and the regulation of Puma induction and suggest that this may be pivotal to the regulation of neuronal apoptosis in neurodegenerative conditions

The JNK and AKT/GSK3β pathways signal independently during potassium withdrawal in CGNs.

<p><b>A,</b> CGNs were maintained in high potassium medium (K25) or subjected to potassium withdrawal (K5) in the presence or absence of the JNK inhibitor SP600125 (10 µM) or the GSK3β inhibitor SB415286 (30 µM). Protein extracts were collected at 2, 4 and 6 hours and Phospho-ATF2, Phospho-c-Jun and ATF3 levels were analyzed by western blot. <b>B,</b> CGNs were subjected to potassium withdrawal in the presence or absence of 200 nM IGF-1. Protein extracts were collected after 6 hours and were analyzed for Phospho-ATF2, Phospho-c-Jun and ATF3 protein levels by western blot. <b>C,</b> CGNs were subjected to potassium withdrawal in the presence or absence of 10 µM SP600125 (SP) and protein extracts were collected after 6 hours and analyzed by western blot for Phospho-AKT and Phospho-GSK3β levels.</p

GSK3β is required for Puma induction in potassium withdrawal induced apoptosis.

<p>CGNs were switched to low potassium medium in the presence or absence of the GSK3α/β inhibitor SB415286 (SB, 30 µM) or the GSK3β specific inhibitor AR-A01 4418 (AR, 50 µM). <b>A,</b> RNA was collected six hours after potassium withdrawal and analyzed for Puma mRNA expression using qRT-PCR (n = 4, *p<0.05). <b>B,</b> Protein extracts were collected 8 hours after potassium withdrawal and Puma protein levels were analyzed by western blot. <b>C,</b> The fraction of apoptotic neurons was quantified after 24 hours by Hoechst staining (n = 3, *p<0.05).</p

JNK is required for Puma induction and potassium withdrawal induced neuronal apoptosis.

<p>After 7 days in culture CGNs were either maintained in high potassium medium or switched to low potassium medium with or without 10 µM SP600125 (SP). <b>A,</b> Puma mRNA levels were assessed by qRT-PCR 6 hours after potassium withdrawal and are reported as fold increase over K25 controls (n = 7, *p<0.05). <b>B,</b> Protein extracts were collected 8 hours after potassium withdrawal and Phospho-ATF2, Phospho-c-Jun, ATF3 and Puma protein levels were assessed by western blot. Calnexin was included as a loading control. <b>C,</b> The fraction of apoptotic neurons was determined 24 hours after potassium withdrawal by examining nuclear morphology in Hoechst stained cells (n = 5, *p<0.05).</p

Puma expression is induced by potassium withdrawal in cerebellar granule neurons.

<p>After 7 days in culture CGNs were either maintained in media containing 25 mM potassium (K25) or switched to low potassium medium containing 5 mM potassium (K5). <b>A,</b> RNA was harvested after 4, 6 and 8 hours and Puma, Bim and Hrk expression was analyzed by qRT-PCR. Expression was normalized to ribosomal S12 levels and is reported as fold increase over untreated controls (n = 4, p<0.05). <b>B,</b> Protein extracts were collected from CGNs derived from Puma+/+ and Puma−/− littermates or Bim+/+ and Bim−/− littermates 8 hours after potassium withdrawal and Puma and Bim protein levels were analyzed by western blot. Actin was included as a loading control.</p

Puma is essential for potassium-withdrawal induced apoptosis in CGNs.

<p>CGNS derived Puma+/+ and Puma−/− littermates were maintained in high potassium medium (K25) or switched to low potassium medium (K5). <b>A,</b> The fraction of apoptotic cells was determined at 24 h by assessing nuclear morphology following Hoechst staining of Puma+/+ vs Puma−/− CGNs (n = 7, *p<0.01). <b>B,</b> Representative images of Hoechst stained wild type and Puma-deficient neurons 24 hours following potassium withdrawal. <b>C,</b> CGNs were stained with Mitotracker Red to assess mitochondrial membrane potential. The fraction of Mitotracker Red labeled neurons was determined 20 hours after potassium withdrawal and compared between genotypes (n = 4, *p<0.05). <b>D,</b> Cell lysates were collected 20 hours after potassium withdrawal and assayed for caspase-3-like activity. Caspase activity is reported as relative fluorescence units of cleaved caspase substrate and was compared between genotypes (n = 4,* p<0.05). <b>E,</b> CGNs derived from Bim+/+ and Bim−/− littermates were maintained in high potassium medium or switched to low potassium medium and the fraction of apoptotic cells was determined at 24 h (n = 5).</p

AKT inactivation induces Puma expression and neuronal apoptosis via a GSK3β-dependent mechanism.

<p>CGNs maintained for 7 days in high potassium medium were treated with or without the PI3K inhibitor LY294002 (30 µM, LY) in the presence or absence of the GSK3β inhibitor SB415286 (30 µM, SB). <b>A,</b> RNA was collected 8 hours post treatment and Puma mRNA levels were determined by qRT-PCR (n = 3,* p<0.05). <b>B,</b> Protein extracts were collected 12 hours post-treatment and Puma protein levels were analyzed by western blot. <b>C,</b> The fraction of apoptotic neurons was quantified after 24 hours by Hoechst staining (n = 3, *p<0.05).</p