Sex differences in heart disease prevalence among individuals with spinal cord injury: A population-based study.

CONTEXT/OBJECTIVE: The risk for cardiovascular disease is amplified following spinal cord injury, but whether risk differs between the sexes remains unknown. Here, we evaluated sex differences in the prevalence of heart disease among individuals with spinal cord injury, and compared sex differences with able-bodied individuals. DESIGN: The design was a cross-sectional study. Multivariable logistic regression analysis was conducted, using inverse probability weighting to account for the sampling method and to adjust for confounders. SETTING: Canada. PARTICIPANTS: Individuals who participated in the national Canadian Community Health Survey. INTERVENTIONS: Not applicable. OUTCOME MEASURES: Self-reported heart disease. RESULTS: Among 354 individuals with spinal cord injury, the weighted prevalence of self-reported heart disease was 22.9% in males and 8.7% in females, with an inverse-probability weighted odds ratio of 3.44 (95% CI 1.70-6.95) for males versus females. Among 60,605 able-bodied individuals, the prevalence of self-reported heart disease was 5.8% in males and 4.0% in females, with an inverse probability weighted odds ratio of 1.62 (95% CI 1.50-1.75) for males versus females. The effect of male sex on increasing heart disease prevalence was about two times higher among individuals with spinal cord injury than able-bodied individuals (relative difference in inverse probability weighted odds ratios = 2.12, 95% CI 1.08-4.51). CONCLUSION: Males with spinal cord injury exhibit a significantly higher prevalence of heart disease, compared with females with spinal cord injury. Moreover, relative to able-bodied individuals, spinal cord injury amplifies sex-related differences in heart disease. Overall, this work will inform targeted cardiovascular prevention strategies, and may also inform a better understanding of cardiovascular disease progression in both able-bodied and individuals with spinal cord injury.

Time of coronary revascularization: methodology of a mediation analysis study.

BACKGROUND: The advantage of coronary artery bypass grafting (CABG) over percutaneous coronary intervention (PCI), established in trials, may not be generalizable to populations in which the method of treatment determines the time to treatment. We sought to describe the methodology of a population-based observational study for assessing how changes in time to treatment may affect the comparative effectiveness of these 2 methods of coronary revascularization. METHODS: We propose a framework of causal mediation analysis to compare the outcomes of choosing CABG over PCI, if patients selected for either method waited the same amount of time had they undergone a PCI. We will include patients who underwent a first-time, nonurgent isolated CABG or single-session PCI for multivessel or left main coronary artery disease from January 2001 to December 2016, in British Columbia. We will use absolute risk difference as a measure of the total effect of choosing CABG over PCI and partition it into the direct effect of the treatment choice and the effect mediated by the treatment-specific timing. INTERPRETATION: Understanding how time to treatment mediates the relation between method of revascularization and outcomes will have implications for treatment selection, resource allocation and planning benchmarks. Findings on the benefits and risks of performing PCI or CABG within a certain time will guide multidisciplinary teams in determining the appropriate revascularization method for individual patients.

A systematic, concept-based method of developing the exposure measure for drug safety and effectiveness studies.

PURPOSE: In drug safety and effectiveness studies based on secondary data, the choice of an appropriate exposure measure for a given outcome can be challenging. Different measures of exposure can yield different estimates of treatment effect and safety. There is a knowledge gap with respect to developing and refining measures of drug exposure, to ensure that the exposure measure addresses the study question and is suitable for statistical analysis. METHODS: We present a transparent, step-by-step approach to the development of drug exposure measures involving secondary data. This approach would be of interest to students and investigators with initial training in pharmacoepidemiology. We illustrate the approach using a study about Parkinson's disease. RESULTS: We described the exposure specifications according to the study question. Next, we refined the exposure measure by linking it to knowledge about four major concepts in drug safety and effectiveness studies: drug use patterns, duration, timing, and dose. We then used this knowledge to guide the ultimate choice of exposure measure: time-varying, cumulative 6-month exposure to tamsulosin (a drug used to treat prostate hyperplasia). CONCLUSIONS: The proposed approach links exposure specifications to four major concepts in drug safety and effectiveness studies. Formulating subject-matter knowledge about these major concepts provides an avenue to develop the rationale and specifications for the exposure measure.

Variation in surgical demand and time to hip fracture repair: a Canadian database study.

BACKGROUND: Competing demands for operative resources may affect time to hip fracture surgery. We sought to determine the time to hip fracture surgery by variation in demand in Canadian hospitals. METHODS: We obtained discharge abstracts of 151,952 patients aged 65 years or older who underwent surgery for a hip fracture between January, 2004 and December, 2012 in nine Canadian provinces. We compared median time to surgery (in days) when demand could be met within a two-day benchmark and when demand required more days, i.e. clearance time, to provide surgery, overall and stratified by presence of medical reasons for delay. RESULTS: For persons admitted when demand corresponded to a 2-day clearance time, 68% of patients underwent surgery within the 2-day benchmark. When demand corresponded to a clearance time of one week, 51% of patients underwent surgery within 2 days. Compared to demand that could be served within the two-day benchmark, adjusted median time to surgery was 5.1% (95% confidence interval [CI] 4.1-6.1), 12.2% (95% CI 10.3-14.2), and 22.0% (95% CI 17.7-26.2) longer, when demand required 4, 6, and 7 or more days to clear the backlog, respectively. After adjustment, delays in median time to surgery were similar for those with and without medical reasons for delay. CONCLUSION: Increases in demand for operative resources were associated with dose-response increases in the time needed for half of hip fracture patients to undergo surgery. Such delays may be mitigated through better anticipation of day-to-day supply and demand and increased response capability.

Constructing treatment episodes from concomitant medication logs: a prospective observational study.

OBJECTIVES: To describe an approach using concomitant medication log records for the construction of treatment episodes. Concomitant medication log records are routinely collected in clinical studies. Unlike prescription and dispensing records, concomitant medication logs collect utilisation data. Logs can provide information about drug safety and drug repurposing. DESIGN: A prospective multicentre, multicohort observational study. SETTING: Twenty-one clinical sites in the USA, Europe, Israel and Australia. PARTICIPANTS: 415 subjects from the de novo cohort of the Parkinson's Progression Markers Initiative. METHODS: We construct treatment episodes of concomitant medication use. The proposed approach treats temporal gaps as a stoppage of medication and temporal overlaps as simultaneous use or changes in dose. Log records with no temporal gaps were combined into a single treatment episode. RESULTS: 5723 concomitant medication log records were used to construct 3655 treatment episodes for 65 medications. There were 405 temporal gaps representing a stoppage of medication; 985 temporal overlaps representing simultaneous regimens of the same medication and 2696 temporal overlaps representing a change in dose regimen. The median episode duration was 37 months (IQ interval: 11-73 months). CONCLUSIONS: The proposed approach for constructing treatment episodes offers a method of estimating duration and dose of treatment from concomitant medication log records. The accompanying recommendations guide log data collection to improve their quality for drug safety and drug repurposing.

Operationalising a conceptual framework for a contiguous hospitalisation episode to study associations between surgical timing and death after first hip fracture: a Canadian observational study.

OBJECTIVE: We describe steps to operationalise a published conceptual framework for a contiguous hospitalisation episode using acute care hospital discharge abstracts. We then quantified the degree of bias induced by a first abstract episode, which does not account for hospital transfers. DESIGN: Retrospective observational study. SETTING: All acute care hospitals in nine Canadian provinces. PARTICIPANTS: We retrieved acute hospitalisation discharge abstracts for 189 448 patients aged 65 years and older admitted to acute care with hip fracture between 2003 and 2013. PRIMARY AND SECONDARY OUTCOME MEASURES: The percentage of patients treated surgically, delayed to surgery (defined as two or more days after admission) and dying, between contiguous hospitalisation episodes and the first abstract episodes of care. RESULTS: Using contiguous hospitalisation episodes, 91.6% underwent surgery, 35.7% were delayed two or more days after admission and 6.7% died postoperatively, whereas, using the first abstract only, these percentages were 83.7%, 32.5% and 6.5%, respectively. CONCLUSION: We demonstrate that not accounting for hospital transfers when evaluating the association between surgical timing and death underestimates reporting of the percentage of patients treated surgically and delayed to surgery by 9%, and the percentage who die after surgery by 3%. Researchers must be aware of this potential and avoidable bias as, depending on the purpose of the study, erroneous inferences may be drawn.

Mortality effects of timing alternatives for hip fracture surgery.

BACKGROUND: The appropriate timing of hip fracture surgery remains a matter of debate. We sought to estimate the effect of changes in timing policy and the proportion of deaths attributable to surgical delay. METHODS: We obtained discharge abstracts from the Canadian Institute for Health Information for hip fracture surgery in Canada (excluding Quebec) between 2004 and 2012. We estimated the expected population-average risks of inpatient death within 30 days if patients were surgically treated on day of admission, inpatient day 2, day 3 or after day 3. We weighted observations with the inverse propensity score of surgical timing according to confounders selected from a causal diagram. RESULTS: Of 139 119 medically stable patients with hip fracture who were aged 65 years or older, 32 120 (23.1%) underwent surgery on admission day, 60 505 (43.5%) on inpatient day 2, 29 236 (21.0%) on day 3 and 17 258 (12.4%) after day 3. Cumulative 30-day in-hospital mortality was 4.9% among patients who were surgically treated on admission day, increasing to 6.9% for surgery done after day 3. We projected an additional 10.9 (95% confidence interval [CI] 6.8 to 15.1) deaths per 1000 surgeries if all surgeries were done after inpatient day 3 instead of admission day. The attributable proportion of deaths for delays beyond inpatient day 2 was 16.5% (95% CI 12.0% to 21.0%). INTERPRETATION: Surgery on admission day or the following day was estimated to reduce postoperative mortality among medically stable patients with hip fracture. Hospitals should expedite operating room access for patients whose surgery has already been delayed for nonmedical reasons.

Feasibility of using administrative data for identifying medical reasons to delay hip fracture surgery: a Canadian database study.

PURPOSE: Failure to account for medically necessary delays may lead to an underestimation of early surgery benefits. This study investigated the feasibility of using administrative data to identify the National Institute for Health and Care Excellence (NICE) 124 guideline list of conditions that appropriately delay hip fracture surgery. METHODS: We assembled a list of diagnosis and procedure codes to reflect the NICE 124 conditions. The list was reviewed and updated by an advanced clinical coder. The list was refined by five clinical experts. We then screened Canadian Institute for Health Information discharge abstracts for 153 918 patients surgically treated for a non-pathological first hip fracture between 1 January 2004 and 31 December 2012 for diagnosis codes present on admission and procedure codes that antedated hip fracture surgery. We classified abstracts as having medical reasons for delaying surgery based on the presence of these codes. RESULTS: In total, 10 237 (6.7%; 95% CI 6.5% to 6.8%) patients had diagnostic and procedure codes indicating medical reasons for delay. The most common reasons for medical delay were exacerbation of a chronic chest condition (35.9%) and acute chest infection (23.2%). The proportion of patients with reasons for medical delays increased with time from admission to surgery: 3.9% (95% CI 3.6% to 4.1%) for same day surgery; 4.7% (95% CI 4.5% to 4.8%) for surgery 1 day after admission; 7.1% (95% CI 6.9% to 7.4%) for surgery 2 days after admission; and 15.5% (95% CI 15.1% to 16.0%) for surgery more than 2 days after admission. The trend was seen for admissions on weekday working hours, weekday after hours and on weekends. CONCLUSION: Administrative data can be considered to identify conditions that appropriately delay hip fracture surgery. Accounting for medically necessary delays can improve estimates of the effectiveness of early surgery.

Feasibility of administrative data for studying complications after hip fracture surgery.

PURPOSE: There is limited information in administrative databases on the occurrence of serious but treatable complications after hip fracture surgery. This study sought to determine the feasibility of identifying the occurrence of serious but treatable complications after hip fracture surgery from discharge abstracts by applying the Agency for Healthcare Research and Quality (AHRQ) Patient Safety Indicator 4 (PSI-4) case-finding tool. METHODS: We obtained Canadian Institute for Health Information discharge abstracts for patients 65 years or older, who were surgically treated for non-pathological first hip fracture between 1 January 2004 and 31 December 2012 in Canada, except for Quebec. We applied specifications of AHRQ Patient Safety Indicators 04, Version 5.0 to identify complications from hip fracture discharge abstracts. RESULTS: Out of 153 613 patients admitted with hip fracture, we identified 12 383 (8.1%) patients with at least one postsurgical complication. From patients with postsurgical complications, we identified 3066 (24.8%) patient admissions to intensive care unit. Overall, 7487 (4.9%) patients developed pneumonia, 1664 (1.1%) developed shock/myocardial infarction, 651 (0.4%) developed sepsis, 1862 (1.1%) developed deep venous thrombosis/pulmonary embolism and 1919 (1.3%) developed gastrointestinal haemorrhage/acute ulcer. CONCLUSIONS: We report that 8.1% of patients developed at least one inhospital complication after hip fracture surgery in Canada between 2004 and 2012. The AHRQ PSI-4 case-finding tool can be considered to identify these serious complications for evaluation of postsurgical care after hip fracture.

Hospital mortality after hip fracture surgery in relation to length of stay by care delivery factors: A database study.

Two hypotheses were offered for the effect of shorter hospital stays on mortality after hip fracture surgery: worsening the quality of care and shifting death occurrence to postacute settings.We tested whether the risk of hospital death after hip fracture surgery differed across years when postoperative stays shortened, and whether care factors moderated the association.Analysis of acute hospital discharge abstracts for subgroups defined by hospital type, bed capacity, surgical volume, and admission time.153,917 patients 65 years or older surgically treated for first hip fracture.Risk of hospital death.We found a decrease in the 30-day risk of hospital death from 7.0% (95%CI: 6.6-7.5) in 2004 to 5.4% (95%CI: 5.0-5.7) in 2012, with an adjusted odds ratio [OR] 0.71 (95%CI: 0.63-0.80). In subgroup analysis, only large community hospitals showed the reduction of ORs by calendar year. No trend was observed in teaching and medium community hospitals. By 2012, the risk of death in large higher volume community hospitals was 34% lower for weekend admissions, OR = 0.66 (95%CI: 0.46-0.95) and 39% lower for weekday admissions, OR = 0.61 (95%CI: 0.40-0.91), compared to 2004. In large lower volume community hospitals, the 2012 risk was 56% lower for weekend admissions, OR = 0.44 (95%CI: 0.26-0.75), compared to 2004.The risk of hospital death after hip fracture surgery decreased only in large community hospitals, despite universal shortening of hospital stays. This supports the concern of worsening the quality of hip fracture care due to shorter stays.

The burden of second hip fractures: provincial surgical hospitalizations over 15 years.

BACKGROUND: Second hip fractures account for up to 15% of all hip fractures. We sought to determine if the proportion of hip fracture surgeries for second hip fracture changed over time in terms of patient and fracture characteristics. METHODS: We reviewed the records of patients older than 60 years hospitalized for hip fracture surgery between 1990 and 2005 in British Columbia. We studied the proportion of surgeries for second hip fracture among all hip fracture surgeries. Linear regression tested for trends across fiscal years for women and men. RESULTS: We obtained 46 341 patient records. Second hip fracture accounted for 8.3% of hip fracture surgeries. For women the proportion of second hip fracture surgeries increased linearly from 4% to 13% with each age decade (p = 0.001) and across fiscal years (p = 0.002). In men the proportion of second hip fracture surgeries was 5% for each age decade between the ages of 60 and 90 years across fiscal years, increasing to 8% for men older than 90 years across fiscal years (p = 0.20). These sex-specific trends were similar for both pertrochanteric and transcervical fracture types. CONCLUSION: Second hip fracture surgeries account for an increasing proportion of hip fracture surgeries and may require more health care resources to minimize poorer reported outcomes. Future research should determine whether more health care resources are required to manage these patients and optimize their outcomes.

CONTEXTE: Les secondes fractures de la hanche représentent jusqu'à 15 % de la totalité des fractures de la hanche. Nous avons tenté de déterminer si la proportion de chirurgies de seconde fracture de la hanche avait évolué au fil du temps sur le plan des caractéristiques des patients et des fractures. MÉTHODES: Nous avons examiné les dossiers des patients de 60 ans et plus qui avaient été hospitalisés pour une chirurgie de fracture de la hanche entre 1990 et 2005, en Colombie-Britannique. De ce total, nous avons ensuite déterminé le nombre de chirurgies de seconde fracture de la hanche. L'analyse de régression linéaire a déterminé les tendances au cours des années financières pour les femmes et les hommes. RÉSULTATS: Nous avons obtenu 46 341 dossiers de patient. Les secondes fractures de la hanche représentaient 8,3 % de la totalité des chirurgies de fracture de la hanche. Chez les femmes, la proportion de seconde fracture de la hanche augmentait de façon linéaire de 4 % à 13 % pour chaque tranche d'âge de 10 ans (p = 0,001) et sur l'ensemble des années financières (p = 0,002). Chez les hommes, la proportion de chirurgies de seconde fracture de la hanche était de 5 % pour chaque tranche d'âge de 10 ans entre 60 et 90 ans et sur l'ensemble des années financières, et augmentait à 8 % pour les hommes de plus de 90 ans sur l'ensemble des années financières (p = 0,20). Ces tendances selon le sexe étaient similaires tant pour les fractures pertrochantériennes que pour les fractures transcervicales. CONCLUSION: Les chirurgies de seconde fracture de la hanche représentent une proportion croissante de la totalité des chirurgies de fracture de la hanche et pourraient nécessiter davantage de ressources en soins de santé pour minimiser les résultats moins bons signalés. Les recherches futures devraient déterminer s'il faut davantage de ressources de soins de santé pour la prise en charge de ces patients et l'optimisation de leurs résultats.

In-hospital mortality after hip fracture by treatment setting.

BACKGROUND: Where patients with hip fracture undergo treatment may influence their outcome. We compared the risk of in-hospital death after hip fracture by treatment setting in Canada. METHODS: We examined all discharge abstracts from the Canadian Institute for Health Information with diagnosis codes for hip fracture involving patients 65 years and older who were admitted to hospital with a nonpathological first hip fracture between Jan. 1, 2004, and Dec. 31, 2012, in Canada (excluding Quebec). We compared the risk of in-hospital death, overall and after surgery, between teaching hospitals and community hospitals of various bed capacities, accounting for variation in length of stay. RESULTS: Compared with the number of deaths per 1000 admissions at teaching hospitals, there were an additional 3 (95% confidence interval [CI] 1-6), 14 (95% CI 10-18) and 43 (95% CI 35-51) deaths per 1000 admissions at large, medium and small community hospitals, respectively. For the risk of in-hospital death overall, the adjusted odds ratios (ORs) were 1.05 (95% CI 0.99-1.11), 1.16 (95% CI 1.09-1.24) and 1.44 (95% CI 1.31-1.57) at large, medium and small community hospitals, respectively, compared with teaching hospitals. For the risk of postsurgical death in hospital, the adjusted ORs were 1.06 (95% CI 1.00-1.13), 1.13 (95% CI 1.04-1.23) and 1.18 (95% CI 0.87-1.60) at large, medium and small community hospitals, respectively. INTERPRETATION: Compared with teaching hospitals, the risk of in-hospital death among patients with hip fracture was higher at medium and small community hospitals, and the risk of in-hospital death after surgery was higher at medium community hospitals. No differences were found between teaching and large community hospitals. Future research should examine the role of volume, demand and bed occupancy for observed differences.

Time trends in hospital stay after hip fracture in Canada, 2004-2012: database study.

UNLABELLED: Changes in bed management and access policy aimed to shorten Canadian hip fracture hospital stay. Secular trends in hip fracture total, preoperative, and postoperative stay are unknown. Hip fracture stay shortened from 2004 to 2012, mostly from shortening postoperative stay. This may reflect changes in bed management rather than access policy. PURPOSE: To compare the probability of discharge by time after patient admission to hospital with first-time hip fracture over a period of nine calendar years. METHODS: We retrieved acute hospitalization records for 169,595 patients 65 years and older, who were admitted to an acute care hospital with hip fracture between 2004 and 2012 in Canada (outside of Quebec). The main outcome measure was cumulative incidence of discharge by inpatient day, accounting for competing events that end hospital stay. RESULTS: The probability of surgical discharge within 30 days of admission increased from 57.2 % in 2004 to 67.3 % in 2012. The probability of undergoing surgery on day of admission or day after fluctuated around 58.5 % over the study period. For postoperative stay, the discharge probability increased from 6.8 to 12.2 % at day 4 after surgery and from 57.2 to 66.6 % at day 21 after surgery, between 2004 and 2012. The differences across years persisted after adjustment for characteristics of patients, fracture, comorbidity, treatment, type and timing of surgery, and access to care. CONCLUSIONS: Hospital stay following hip fracture shortened substantially between 2004 and 2012 in Canada, mostly due to shortening of postoperative stays. Shorter hospital stays may reflect changes in bed management protocols rather than in access policy.

Constructing an episode of care from acute hospitalization records for studying effects of timing of hip fracture surgery.

Episodes of care defined by the event of hip fracture surgery are widely used for the assessment of surgical wait times and outcomes. However, this approach does not consider nonoperative deaths, implying that survival time begins at the time of procedure. This approach makes treatment effect implicitly conditional on surviving to treatment. The purpose of this article is to describe a novel conceptual framework for constructing an episode of hip fracture care to fully evaluate the incidence of adverse events related to time after admission for hip fracture. This admission-based approach enables the assessment of the full harm of delay by including deaths while waiting for surgery, not just deaths after surgery. Some patients wait until their conditions are optimized for surgery, whereas others have to wait until surgical service becomes available. We provide definitions, linkage rules, and algorithms to capture all hip fracture patients and events other than surgery. Finally, we discuss data elements for stratifying patients according to administrative factors for delay to allow researchers and policymakers to determine who will benefit most from expedited access to surgery.

24/7 Registered Nurse Staffing Coverage in Saskatchewan Nursing Homes and Acute Hospital Use.

RÉSUMÉ La législation, dans de nombreuses juridictions, nécessite les établissements des soins de longue durée (SLD) d'avoir une infirmière en service 24 heures par jour, 7 jours par semaine. Bien que la recherche considérable existe sur l'intensité SLD de la dotation en personnel infirmier, il n'existe pas de la recherche empirique relative à cette exigence. Notre étude rétrospectif d'observation a comparé des installations en Saskatchewan avec 24/7 RN couverture aux établissements offrant moins de couverture, complétées par divers modèles de dotation des postes de nuit. Les ratios de risque associés à moins de 24/7 couverture RN complété de la dotation infirmière autorisé de nuit, ajusté pour l'intensité de dotation en personnel infirmier et d'autres facteurs de confusion potentiels, étaient de 1,17, IC 95% [0,91, 1,50] et 1.00, IC à 95% [0,72, 1,39], et avec moins de couverture 24/7 RN complété avec soin par aides personnels de nuit, les ratios de risque étaient de 1,46, IC 95% [1,11, 1,91] et 1,11, IC 95% [0,78, 1,58], pour les patients hospitalisés et de visites aux services d'urgence, respectivement. Ces résultats suggèrent que l'utilisation des soins de courte durée peut être influencée négativement par l'absence de la couverture 24/7 RN.

Risk of second hip fracture persists for years after initial trauma.

BACKGROUND: Secondary prevention often targets women who suffer from higher rates of second hip fracture than men, especially in the early years after first fracture. Yet, the occurrence of second hip fracture by certain times also depends on the death rate, which is higher in men than women. We compared the risk of sustaining second hip fracture by a certain time between women and men remaining alive at that time. METHODS: We retrieved 38,383 hospitalization records of patients aged 60 years or older, who were discharged alive after admission for hip fracture surgery between 1990 and 2005 in British Columbia, Canada. The outcome variable was the time to a subsequent hip fracture. RESULTS: During ten years of follow-up, 2,902 (8%) patients sustained a second hip fracture, and 21,428 (56%) died before sustaining a second hip fracture. The risk of second hip fracture in the surviving post-fracture patients was higher in women than in men: 2% vs 2%, 5% vs 4%, 9% vs 7%, 15% vs 13%, and 35% vs 30% at 1, 2, 3, 5, and 10 years after initial trauma, respectively, crude OR=1.25 (95% CI: 1.13-1.39). However, the risk did not differ between women and men after adjustment, OR=1.09 (95% CI: 0.98-1.21). CONCLUSIONS: The risk of second hip fracture persists for at least ten years among hip fracture survivors, and therefore secondary prevention should continue beyond an early post-fracture period. Women and men have similar risks of second hip fracture and both should be considered for secondary prevention.

Nursing home characteristics associated with resident transfers to emergency departments.

This study examined how nursing home facility ownership and organizational characteristics relate to emergency department (ED) transfer rates. The sample included a retrospective cohort of nursing home residents in the Vancouver Coastal Health region (n = 13,140). Rates of ED transfers were compared between nursing home ownership types. Administrative data were further linked to survey-derived data of facility organizational characteristics for exploratory analysis. Crude ED transfer rates (transfers/100 resident years) were 69, 70, and 51, respectively, in for-profit, non-profit, and publicly owned facilities. Controlling for sex and age, public ownership was associated with lower ED transfer rates compared to for-profit and non-profit ownership. Results showed that higher total direct-care nursing hours per resident day, and presence of allied health staff--disproportionately present in publicly owned facilities--were associated with lower transfer rates. A number of other facility organizational characteristics--unrelated to ownership--were also associated with transfer rates.

The nature of progression in Parkinson's disease: an application of non-linear, multivariate, longitudinal random effects modelling.

BACKGROUND: To date, statistical methods that take into account fully the non-linear, longitudinal and multivariate aspects of clinical data have not been applied to the study of progression in Parkinson's disease (PD). In this paper, we demonstrate the usefulness of such methodology for studying the temporal and spatial aspects of the progression of PD. Extending this methodology further, we also explore the presymptomatic course of this disease. METHODS: Longitudinal Positron Emission Tomography (PET) measurements were collected on 78 PD patients, from 4 subregions on each side of the brain, using 3 different radiotracers. Non-linear, multivariate, longitudinal random effects modelling was applied to analyze and interpret these data. RESULTS: The data showed a non-linear decline in PET measurements, which we modelled successfully by an exponential function depending on two patient-related covariates duration since symptom onset and age at symptom onset. We found that the degree of damage was significantly greater in the posterior putamen than in the anterior putamen throughout the disease. We also found that over the course of the illness, the difference between the less affected and more affected sides of the brain decreased in the anterior putamen. Younger patients had significantly poorer measurements than older patients at the time of symptom onset suggesting more effective compensatory mechanisms delaying the onset of symptoms. Cautious extrapolation showed that disease onset had occurred some 8 to 17 years prior to symptom onset. CONCLUSIONS: Our model provides important biological insights into the pathogenesis of PD, as well as its preclinical aspects. Our methodology can be applied widely to study many other chronic progressive diseases.