The association of time and medications with changes in bone mineral density in the 2 years after critical illness

Vitamin D Supplementation in Critically Ill-Narrative Review

BACKGROUND

Studies have shown a high prevalence of vitamin D deficiency in critically ill patients, and these patients are at higher risk for pneumonia and have increased incidence of sepsis and mortality. In this study, we reviewed available literature from randomized controlled trials (RCTs) on vitamin D supplementation in critically ill patients and summarized the evidence in this narrative review.

METHODS

Randomized controlled trials that included vitamin D supplementation as an intervention were eligible for inclusion. No limits were set regarding vitamin D dosage or route of administration, as well as for primary and secondary outcomes. A search was conducted in MEDLINE via PubMed for eligible RCTs. References from systematic reviews (SRs) and meta-analyses (MAs) were screened, and Clinicaltrials.gov was searched for ongoing studies.

RESULTS

A total of 21 RCTs involving 3166 patients were analyzed. There was a large heterogeneity in terms of patients' characteristics and inclusion criteria. Only six studies included patients with vitamin D levels < 50 nmol/L. Regarding clinically important outcomes, most of the studies did not show differences between the intervention and control group in terms of mortality, intensive care unit (ICU) or hospital length of stay (LoS).

CONCLUSIONS

There is great variability in trial designs regarding the selection of patients, dosage, dosing intervals and routes of administration of vitamin D supplements. Better study designs are mandatory for future clinical research, with measuring and reporting basal vitamin D levels before randomization. Since variability in supplementation regimes limits the possibility of data synthesis, standardized protocols for vitamin D supplementation should be used in clinical trial settings.

GENETIC PREDICTION OF CAUSAL RELATIONSHIPS BETWEEN OSTEOPOROSIS AND SEPSIS: EVIDENCE FROM MENDELIAN RANDOMIZATION WITH TWO-SAMPLE DESIGNS

ABSTRACT

Background: Recent observational studies have suggested that osteoporosis may be a risk factor for sepsis. To mitigate confounding factors and establish the causal relationship between sepsis and osteoporosis, we conducted a two-sample Mendelian randomization analysis using publicly available summary statistics. Methods: Utilizing summary data from FinnGen Biobank, we employed a two-sample Mendelian randomization (MR) analysis to predict the causal relationship between osteoporosis and sepsis. The MR analysis primarily utilized the inverse variance weighted (IVW) method, supplemented by MR-Egger, weighted median, weighted mode, and simple mode analyses, with Bayesian weighted MR (BWMR) analysis employed for result validation. Sensitivity analyses included MR-PRESSO, "leave-one-out" analysis, MR-Egger regression, and Cochran Q test. Results: In the European population, an increase of one standard deviation in osteoporosis was associated with an 11% increased risk of sepsis, with an odds ratio (OR) of 1.11 (95% CI, 1.06-1.16; P = 3.75E-06). BWMR yielded an OR of 1.11 (95% CI, 1.06-1.67; P = 1.21E-05), suggesting osteoporosis as a risk factor for sepsis. Conversely, an increase of one standard deviation in sepsis was associated with a 26% increased risk of osteoporosis, with an OR of 1.26 (95% CI, 1.11-1.16; P = 0.45E-03). BWMR yielded an OR of 1.26 (95% CI, 1.09-1.45; P = 1.45E-03), supporting sepsis as a risk factor for osteoporosis. Conclusion: There is an association between osteoporosis and sepsis, with osteoporosis serving as a risk factor for the development of sepsis, while sepsis may also promote the progression of osteoporosis.

Bone Mineral Density, Bone Biomarkers, and Joints in Acute, Post, and Long COVID-19: A Systematic Review

SARS-CoV-2 is highly transmissible and affects the respiratory system. People with COVID-19 are at higher risk of physical and mental health conditions, which could impact bone health. The aim of this review was to explore the effects of COVID-19 on BMD, BTMs, and joints. An electronic search of the PubMed, Web of Science, Scopus, and Ovid Medline databases considered studies published between 1 January 2020 and 1 November 2023. The search was limited to English, original studies in adult humans. The title and abstract of the identified papers were screened, followed by a full-text review using inclusion and exclusion criteria. The data extracted included the study and participant characteristics, BTMs, BMD, and joint abnormalities. The Newcastle-Ottawa scale quality assessment tool was used to assess the risk of bias. Five studies involving 305 out of 495 infected individuals observed a reduced BMD after COVID-19, with the most significant reduction occurring a year later. Both bone resorption and bone formation markers decreased, while regulatory markers showed higher levels in infected patients. COVID-19 may harm bone health by increasing bone regulatory markers and reducing bone formation and absorption, leading to a lower BMD. Elderly, frail, and osteopenic or osteoporotic individuals are at higher risk and should be regularly monitored for bone loss if they have long COVID.

Survivorship outcomes for critically ill patients in Australia and New Zealand: A scoping review

INTRODUCTION

Impairments after critical illness, termed the post-intensive care syndrome, are an increasing focus of research in Australasia. However, this research is yet to be cohesively synthesised and/or summarised.

OBJECTIVE

The aim of this scoping review was to explore patient outcomes of survivorship research, identify measures, methodologies, and designs, and explore the reported findings in Australasia.

INCLUSION CRITERIA

Studies reporting outcomes for adult survivors of critical illness from Australia and New Zealand in the following domains: physical, functional, psychosocial, cognitive, health-related quality of life (HRQoL), discharge destination, health care use, return to work, and ongoing symptoms/complications of critical illness.

METHODS

The Joanna Briggs Institute scoping review methodology framework was used. A protocol was published on the open science framework, and the search used Ovid MEDLINE, Scopus, ProQuest, and Google databases. Eligible studies were based on reports from Australia and New Zealand published in English between January 2000 and March 2022.

RESULTS

There were 68 studies identified with a wide array of study aims, methodology, and designs. The most common study type was nonexperimental cohort studies (n = 17), followed by studies using secondary analyses of other study types (n = 13). HRQoL was the most common domain of recovery reported. Overall, the identified studies reported that impairments and activity restrictions were associated with reduced HRQoL and reduced functional status was prevalent in survivors of critical illness. About 25% of 6-month survivors reported some form of disability. Usually, by 6 to12 months after critical illness, impairments had improved.

CONCLUSIONS

Reports of long-term outcomes for survivors of critical illness in Australia highlight that impairments and activity limitations are common and are associated with poor HRQoL. There was little New Zealand-specific research related to prevalence, impact, unmet needs, ongoing symptoms, complications from critical illness, and barriers to recovery.

A pilot feasibility randomised controlled trial of bone antiresorptive agents on bone turnover markers in critically ill women

Critical illness is associated with increased bone turnover, loss of bone density, and increased risk of fragility fractures. The impact of bone antiresorptive agents in this population is not established. This trial examined the efficacy, feasibility, and safety of antiresorptive agents administered to critically ill women aged fifty years or greater. Women aged 50 years or greater admitted to an intensive care unit for at least 24 h were randomised to receive an antiresorptive agent (zoledronic acid or denosumab) or placebo, during critical illness and six months later (denosumab only). Bone turnover markers and bone mineral density (BMD) were monitored for 1 year. We studied 18 patients over 35 months before stopping the study due to the COVID-19 pandemic. Antiresorptive medications decreased the bone turnover marker type 1 cross-linked c-telopeptide (CTX) from day 0 to 28 by 43% (± 40%), compared to an increase of 26% (± 55%) observed with placebo (absolute difference - 69%, 95% CI - 127% to - 11%), p = 0.03). Mixed linear modelling revealed differences in the month after trial drug administration between the groups in serum CTX, alkaline phosphatase, parathyroid hormone, and phosphate. Change in BMD between antiresorptive and placebo groups was not statistically analysed due to small numbers. No serious adverse events were recorded. In critically ill women aged 50-years and over, antiresorptive agents suppressed bone resorption markers without serious adverse events. However, recruitment was slow. Further phase 2 trials examining the efficacy of these agents are warranted and should address barriers to enrolment.Trial registration: ACTRN12617000545369, registered 18th April 2017.

Pathophysiology and Therapeutic Management of Bone Loss in Patients with Critical Illness

Patients with critical illnesses are at higher risk of comorbidities, which can include bone mineral density loss, bone turnover marker increase, and fragility fractures. Patients admitted to intensive care units (ICUs) have a higher risk of bone fractures. Since hypermetabolism is a characteristic of ICU patients, such patients are often rapidly affected by systemic deterioration, which often results in systemic wasting disease. Major risk factors for ICU-related bone loss include physical restraint, inflammation, neuroendocrine stress, malnutrition, and medications. A medical history of critical illness should be acknowledged as a risk factor for impaired bone metabolism. Bone loss associated with ICU admission should be recognized as a key component of post-intensive care syndrome, and further research that focuses on treatment protocols and prevention strategies is required. Studies aimed at maintaining gut integrity have emphasized protein administration and nutrition, while research is ongoing to evaluate the therapeutic benefits of anti-resorptive agents and physical therapy. This review examines both current and innovative clinical strategies that are used for identifying risk factors of bone loss. It provides an overview of perioperative outcomes and discusses the emerging novel treatment modalities. Furthermore, the review presents future directions in the treatment of ICU-related bone loss.

Bone mineral density changes in osteoporotic and osteopenic patients after COVID-19 infection

Background

Coronavirus disease 2019 (COVID-19) infection is linked to high levels of inflammatory cytokines and prolonged immobilization; furthermore, corticosteroid treatment leads to increased bone loss and resorption. We aimed to study the change in bone mineral density (BMD) after COVID-19 infection in osteoporotic and osteopenic patients. One hundred osteoporotic or osteopenic patients were selected in this single-center retrospective study; the patients were divided into two groups. Group 1 included 56 patients who got COVID-19 infection. Group 2 included 44 patients who did not get COVID-19 infection. BMD was assessed at baseline, after 9 months of COVID infection, and then after 1 year follow-up using dual energy x-ray absorptiometry (DXA) scan.

Results

There was no significant difference between two groups regarding demographic data (p > 0.05); there was a significant decrease in BMD of the lumbar region and femur at 9 months as compared to baseline in group1 (p < 0.001), while there was a significant increase in the lumbar BMD of osteoporotic patients who did not get COVID infection after 21 months. Concerning activity of COVID infection, there was a significant difference between the three subgroups of COVID patients regarding percentage of change in BMD after 9 months, the severe group having the highest decrease in BMD (p < 0.001).

Conclusions

COVID-19 may have deleterious effect on BMD in osteoporotic patients. It is recommended to assess BMD in osteoporotic/osteopenic patients who got COVID infection to detect if there is an increased risk of fracture which may necessitate post-COVID change in the therapeutic intervention plan.

Negative calcium balance despite normal plasma ionized calcium concentrations during citrate anticoagulated continuous venovenous hemofiltration (CVVH) in ICU patients

Background

Supplementation of calcium during continuous venovenous hemofiltration (CVVH) with citrate anticoagulation is usually titrated using a target blood ionized calcium concentration. Plasma calcium concentrations may be normal despite substantial calcium loss, by mobilization of calcium from the skeleton. Aim of our study is to develop an equation to calculate CVVH calcium and to retrospectively calculate CVVH calcium balance in a cohort of ICU-patients.

Methods

This is a single-center retrospective observational cohort study. In a subcohort of patients, all calcium excretion measurements in patients treated with citrate CVVH were randomly divided into a development set (n = 324 in 42 patients) and a validation set (n = 441 in 42 different patients). Using mixed linear models, we developed an equation to calculate calcium excretion from routinely available parameters. We retrospectively calculated calcium balance in 788 patients treated with citrate CVVH between 2014 and 2021.

Results

Calcium excretion (mmol/24 h) was − 1.2877 + 0.646*[Ca]blood,total * ultrafiltrate (l/24 h) + 0.107*blood flow (ml/h). The mean error of the estimation was − 1.0 ± 6.7 mmol/24 h, the mean absolute error was 4.8 ± 4.8 mmol/24 h. Calculated calcium excretion was 105.8 ± 19.3 mmol/24 h. Mean daily CVVH calcium balance was − 12.0 ± 20.0 mmol/24 h. Mean cumulative calcium balance ranged from − 3687 to 448 mmol.

Conclusion

During citrate CVVH, calcium balance was negative in most patients, despite supplementation of calcium based on plasma ionized calcium levels. This may contribute to demineralization of the skeleton. We propose that calcium supplementation should be based on both plasma ionized calcium and a simple calculation of calcium excretion by CVVH.

Graphical abstract

Denosumab for Prevention of Acute Onset Immobilization-Induced Alterations of Bone Turnover: A Randomized Controlled Trial

Metabolic bone disease is a devastating condition in critically ill patients admitted to an intensive care unit (ICU). We investigated the effects of early administration of the antiresorptive drug denosumab on bone metabolism in previously healthy patients. Fourteen patients with severe intracerebral or subarachnoid hemorrhage were included in a phase 2 trial. Within 72 hours after ICU admission, they were randomized in a 1:1 ratio to receive denosumab 60 mg or placebo subcutaneously. The primary endpoint was group differences in the percentage change of C-terminal telopeptide of type 1 collagen (CTX-1) levels in serum from denosumab/placebo application to 4 weeks thereafter. Changes in serum levels of bone formation markers and urinary calcium excretion were secondary outcome parameters. Regarding serum levels of CTX-1, changes over time averaged -0.45 ng/mL (95% confidence interval [CI] -0.72, -0.18) for the denosumab group and 0.29 ng/mL (95% CI -0.01, 0.58) for the placebo group. The primary endpoint, the group difference in changes between baseline and secondary measurement, adjusted for baseline serum levels and baseline neurological status, averaged -0.74 ng/mL (95% CI -1.14, -0.34; p = 0.002). The group difference in changes between baseline and secondary osteocalcin measurement averaged -5.60 ng/mL (95% CI -11.2, -0.04; p = 0.049). The group difference in averaged change between baseline and secondary measurement of 24-hour urine calcium excretion was significant (-1.77 mmol/L [95% CI -3.48, -0.06; p = 0.044]). No adverse events could be attributed to the study medication. The investigation proved that a single application of denosumab early after admission to an ICU prevents acute immobilization-associated increase in bone resorption among previously healthy individuals. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Critical illness and bone metabolism: where are we now and what is next?

Critical illness refers to the clinical signs of severe, variable and life-threatening critical conditions, often accompanied by insufficiency or failure of one or more organs. Bone health of critically ill patients is severely affected during and after ICU admission. Therefore, clinical work should focus on ICU-related bone loss, and early development and implementation of related prevention and treatment strategies: optimized and personalized nutritional support (high-quality protein, trace elements and intestinal prebiotics) and appropriate physiotherapy and muscle training should be implemented as early as possible after ICU admission and discharge. At the same time, the drug regulates excessive metabolism and resists osteoporosis.

Acute and severe trabecular bone loss in a rat model of critical illness myopathy

Prolonged mechanical ventilation for critically ill patients with respiratory distress can result in severe muscle wasting with preferential loss of myosin. Systemic inflammation triggered by lung mechanical injury likely contributes to this myopathy, although the exact mechanisms are unknown. In this study, we hypothesized that muscle wasting following mechanical ventilation is accompanied by bone loss. The objective was to determine the rate, nature, and extent of bone loss in the femora of rats ventilated up to 10 days and to relate the bone changes to muscle deterioration. We have developed a rat model of ventilator-induced muscle wasting and established its feasibility and clinical validity. This model involves pharmacologic paralysis, parenteral nutrition, and continuous mechanical ventilation. We assessed the hindlimb muscle and bone of rats ventilated for 0, 2, 5, 8, and 10 days. Routine histology, microCT, and biomechanical evaluations were performed. Hindlimb muscles developed changes consistent with myopathy, whereas the femurs demonstrated a progressive decline in trabecular bone volume, mineral density, and microarchitecture beginning Day 8 of mechanical ventilation. Biomechanical testing showed a reduction in flexural strength and stiffness on Day 10. The bone changes correlated with the loss of muscle mass and myosin. These results demonstrate that mechanical ventilation leads to progressive trabecular bone loss parallel to muscle deterioration. The results of our study suggest that mechanically ventilated patients may be at risk of compromised bone integrity and muscle weakness, predisposing to post-ventilator falls and fractures, thereby warranting interventions to prevent progressive bone and muscle decline.

Postacute Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A State-of-the-Art Review

The vast majority of patients (>99%) with severe acute respiratory syndrome coronavirus 2 survive immediate infection but remain at risk for persistent and/or delayed multisystem. This review of published reports through May 31, 2021, found that manifestations of postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection (PASC) affect between 33% and 98% of coronavirus disease 2019 survivors and comprise a wide range of symptoms and complications in the pulmonary, cardiovascular, neurologic, psychiatric, gastrointestinal, renal, endocrine, and musculoskeletal systems in both adult and pediatric populations. Additional complications are likely to emerge and be identified over time. Although data on PASC risk factors and vulnerable populations are scarce, evidence points to a disproportionate impact on racial/ethnic minorities, older patients, patients with preexisting conditions, and rural residents. Concerted efforts by researchers, health systems, public health agencies, payers, and governments are urgently needed to better understand and mitigate the long-term effects of PASC on individual and population health.

Association of sepsis with risk for osteoporosis: a population-based cohort study

We conducted a large, retrospective cohort study using data from Taiwan's National Health Insurance Research Database to evaluate whether the risk of developing osteoporosis is associated with sepsis. Our study found that adults younger than 65 years with sepsis had a significantly increased risk of developing osteoporosis.

INTRODUCTION

There have been limited studies regarding the osteoporosis risk associated with sepsis. Our purpose is to evaluate whether the risk of developing osteoporosis is associated with sepsis.

METHODS

We conducted a large, retrospective cohort study using data from Taiwan's National Health Insurance Research Database. From the insurance claims data, a total of 13,178 patients diagnosed with sepsis from 2000 to 2012 were included in the sepsis cohort, and a propensity score-matched cohort included 13,178 individuals without sepsis. To calculate the incidence of osteoporosis, both groups were followed until 2013. Cox regression analysis was performed to obtain the hazard ratios (HRs) to assess the risk of developing osteoporosis. The Kaplan-Meier method was used to estimate the cumulative incidence of osteoporosis.

RESULTS

The overall incidences of osteoporosis (per 1,000 person-years) in the sepsis and non-sepsis groups were 10.2 and 10.7, respectively. The risk of osteoporosis significantly increased in the presence of sepsis (adjusted HR = 1.17, 95% confidence interval (CI) = 1.04-1.31). The risk of osteoporosis in the sepsis group was significantly higher than that in the non-sepsis group for young patients aged 20-49 years and patients aged 50-64 years (adjusted HR = 1.93, 95% CI = 1.08-3.44; adjusted HR = 2.01, 95% CI = 1.52-2.65, respectively). The Kaplan-Meier curves of cumulative probability also showed a significantly increased risk of osteoporosis in patients aged 20-49 years and aged 50-64 years with sepsis compared with non-sepsis (P = 0.025; P < 0.001, respectively).

CONCLUSION

Adults younger than 65 years with sepsis had a significantly increased risk of developing osteoporosis.

ICU admission body composition: skeletal muscle, bone, and fat effects on mortality and disability at hospital discharge-a prospective, cohort study

Background

Reduced body weight at the time of intensive care unit (ICU) admission is associated with worse survival, and a paradoxical benefit of obesity has been suggested in critical illness. However, no research has addressed the survival effects of disaggregated body constituents of dry weight such as skeletal muscle, fat, and bone density.

Methods

Single-center, prospective observational cohort study of medical ICU (MICU) patients from an academic institution in the USA. Five hundred and seven patients requiring CT scanning of chest or abdomen within the first 24 h of ICU admission were evaluated with erector spinae muscle (ESM) and subcutaneous adipose tissue (SAT) areas and with bone density determinations at the time of ICU admission, which were correlated with clinical outcomes accounting for potential confounders.

Results

Larger admission ESM area was associated with decreased odds of 6-month mortality (OR per cm², 0.96; 95% CI, 0.94–0.97; p < 0.001) and disability at discharge (OR per cm², 0.98; 95% CI, 0.96–0.99; p = 0.012). Higher bone density was similarly associated with lower odds of mortality (OR per 100 HU, 0.69; 95% CI, 0.49–0.96; p = 0.027) and disability at discharge (OR per 100 HU, 0.52; 95% CI, 0.37–0.74; p < 0.001). SAT area was not significantly associated with these outcomes’ measures. Multivariable modeling indicated that ESM area remained significantly associated with 6-month mortality and survival after adjusting for other covariates including preadmission comorbidities, albumin, functional independence before admission, severity scores, age, and exercise capacity.

Conclusion

In our cohort, ICU admission skeletal muscle mass measured with ESM area and bone density were associated with survival and disability at discharge, although muscle area was the only component that remained significantly associated with survival after multivariable adjustments. SAT had no association with the analyzed outcome measures.

Metabolic and Endocrine Challenges

This review aims to provide an overview of metabolic and endocrine challenges in the setting of intensive care medicine. These are a group of heterogeneous clinical conditions with a high degree of overlap, as well as nonspecific signs and symptoms. Several diseases involve multiple organ systems, potentially causing catastrophic dysfunction and death. In the majority of cases, endocrine challenges accompany other organ failures or manifest as a complication of prolonged intensive care unit stay and malnutrition. However, when endocrine disorders present as an isolated syndrome, they are a rare and extreme manifestation. As they are uncommon, these can typically challenge both with diagnosis and management. Acute exacerbations may be elicited by triggers such as infections, trauma, surgery, and hemorrhage. In this complex scenario, early diagnosis and prompt treatment require knowledge of the specific endocrine syndrome. Here, we review diabetic coma, hyponatremia, hypercalcemia, thyroid emergencies, pituitary insufficiency, adrenal crisis, and vitamin D deficiency, highlighting diagnostic tools and tricks, and management pathways through defining common clinical presentations.

Loss of bone mineral density following sepsis using Hounsfield units by computed tomography

Aim

To examine the change in vertebral bone mineral density (BMD) using abdominal computed tomography in patients treated for sepsis.

Methods

A single‐center, retrospective, observational study was undertaken to evaluate BMD after critical care at Okayama Saiseikai General Hospital (Okayama, Japan) from January 2016 to April 2018. Sepsis was defined as an absolute increase of ≥2 in Sequential Organ Failure Assessment score in the intensive care unit or high care unit. Bone mineral density was evaluated in Hounsfield units (HU) by computed tomography. Patients were divided into groups based on the presence or absence of osteoporosis, which was defined as average vertebral body HU <110. Paired t‐tests were used to compare the mean BMD of each vertebra between before and after critical care. We also analyzed accidental bone fracture events after discharge. The survival rate was analyzed as an outcome using the Kaplan–Meier method.

Results

Fifty‐two of 188 patients met the inclusion criteria. We found significant differences between admission and follow‐up vertebral BMD values in the spine at the thoracic 12, lumbar 1–5, and sacrum 1 levels (P < 0.05), especially in the non‐osteoporosis groups. No difference in mortality was observed between patients with osteoporosis and those without. Two of 19 patients with osteoporosis developed a bone fracture.

Conclusion

We found that sepsis was associated with loss in BMD following critical care.

Bone function, dysfunction and its role in diseases including critical illness

The skeleton is one of the largest organs in the human body. In addition to its conventional functions such as support, movement and protection, the skeleton also contributes to whole body homeostasis and maintenance of multiple important non-bone organs/systems (extraskeletal functions). Both conventional and extraskeletal functions of the skeleton are defined as bone function. Bone-derived factors (BDFs) are key players regulating bone function. In some pathophysiological situations, including diseases affecting bone and/or other organs/systems, the disorders of bone itself and the subsequently impaired functions of extraskeletal organs/systems caused by abnormal bone (impaired extraskeletal functions of bone) are defined as bone dysfunction. In critical illness, which is a health status characterized by the dysfunction or severe damage of one or multiple important organs or systems, the skeleton shows rapid bone loss resulting from bone hyper-resorption and impaired osteoblast function. In addition, the dysfunctions of the skeleton itself are also closely related to the severity and prognosis of critical illness. Therefore, we propose that there is bone dysfunction in critical illness. Some methods to inhibit osteoclast activity or promote osteoblast function by the treatment of bisphosphonates or PTH1-34 benefit the outcome of critical illness, which indicates that enhancing bone function may be a potential novel strategy to improve prognosis of diseases including critical illness.

Osteoporosis and the Critically Ill Patient

Improved survival after critical illness has led to recognition of impaired recovery following critical illness as a major public health problem. A consistent association between critical illness and accelerated bone loss has been described, including changes in bone turnover markers, bone mineral density, and fragility fracture rate. An association between accelerated bone turnover and increased mortality after critical illness is probable. Assessment of the effect of antifracture agents on fracture rate and mortality in the high-risk population of postmenopausal women with prolonged ventilation is warranted.

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

Changes in bone mineral density (BMD): a longitudinal study of osteoporosis patients in the real-world setting

In clinical practice, the frequency of patients achieving improved T-scores and the expected change in bone mineral density (BMD) according to osteoporosis drugs is unknown. We found that osteoporosis medications infrequently achieve improved femoral neck T-scores over 1.2 years. BMD increases were more often seen with IV bisphosphonates and denosumab.

PURPOSE

To determine the frequency of osteoporosis patients achieving improvement in T-scores and quantify the change in bone mineral density (BMD) over time according to osteoporosis medication use.

METHODS

The study included all patients receiving clinical care at United Osteoporosis Centers, Gainesville, GA, 1995-2015, who had at least two measures of femoral neck BMD (N = 1232). We evaluated successive pairs of BMD tests to describe the distribution of transitions between T-score categories. Generalized estimating equations were used to estimate %BMD change between successive pairs of BMD tests according to osteoporosis medication, adjusted for age, sex, height, weight, baseline BMD, previous fracture, and follow-up time.

RESULTS

Mean (±SD) age was 68 (±10) years, and 90% of patients were women. Mean baseline T-score was - 2.04 (± 0.85). In total, 1232 patients had 4918 pairs of successive BMD tests, with a mean 1.2 years (± 0.9) between assessments. Frequency of transition to an improved T-score category was 41% when prior T-score ≤ - 3.5, and 15% when prior T-score - 1.99 to - 1.50. Most individuals (69%) remained in the same T-score category. BMD increased 0.54% (95% CI 0.23-0.85%) with IV bisphosphonates and 1.23% (95% CI 0.56-1.90%) with denosumab, whereas no significant change was seen with oral bisphosphonates, teriparatide, or raloxifene.

CONCLUSIONS

Osteoporosis patients are unlikely to improve femoral neck T-scores over 1.2 years. Additional studies are needed to determine the optimal time to repeat BMD testing while receiving osteoporosis treatment and to determine whether fracture risk is reduced in patients who achieve target T-scores.

Changes in bone mineral density in women before critical illness: a matched control nested cohort study

The contribution of premorbid bone health to accelerated bone loss following critical illness is unknown. This study compared bone density in women before critical illness to women who did not become critically ill. Overall bone density was similar, although femoral neck bone mass increased immediately prior to critical illness.

PURPOSE

The relative contribution of acute and chronic factors to accelerated loss of bone mineral density (BMD) following critical illness is unknown. This study compared the BMD trajectory of women before critical illness to the BMD trajectory of women who did not become critically ill.

METHODS

This prospective, nested, age- and medication-matched, case-control study compared trajectory of BMD in women in the Geelong Osteoporosis study (GOS) requiring admission to an Australian Intensive Care Unit (ICU) between June 1998 and March 2016, to women not admitted to ICU. The main outcome was age and medication use adjusted change in BMD.

RESULTS

A total of 52 women, with a mean age of 77 ± 9 years were admitted to ICU, predominantly post-surgery (75%), during the study period. A greater age-adjusted annual rate of decline was observed for pre-ICU women compared to no-ICU women for AP spine BMD (-0.010 ± 0.002 g/cm² vs -0.005 ± 0.002 g/cm², p = 0.01) over the 15-year study period. In participants with multiple BMDs 2 years before critical illness, a significantly greater increase in femoral neck BMD compared to age- and medication-matched controls was observed (difference in BMD, ICU vs no-ICU = 0.037 ± 0.013 g/cm², p = 0.006).

CONCLUSION

In a cohort of women with predominantly surgical ICU admission, bone health prior to critical illness was comparable to age- and medication-matched controls, with a relative increase in femoral neck bone mass immediately prior to critical illness. These findings suggest critical illness-related bone loss cannot be entirely explained as a continuation of pre-morbid bone trajectory.