Bone mineral density is related to lung function outcomes in young people with cystic fibrosis-A retrospective study

Cystic Fibrosis Bone Disease: The Interplay between CFTR Dysfunction and Chronic Inflammation

Cystic fibrosis is a monogenic disease with a multisystemic phenotype, ranging from predisposition to chronic lung infection and inflammation to reduced bone mass. The exact mechanisms unbalancing the maintenance of an optimal bone mass in cystic fibrosis patients remain unknown. Multiple factors may contribute to severe bone mass reduction that, in turn, have devastating consequences in the patients' quality of life and longevity. Here, we will review the existing evidence linking the CFTR dysfunction and cell-intrinsic bone defects. Additionally, we will also address how the proinflammatory environment due to CFTR dysfunction in immune cells and chronic infection impairs the maintenance of an adequate bone mass in CF patients.

Bisphosphonates for osteoporosis in people with cystic fibrosis

BACKGROUND

Osteoporosis is a disorder of bone mineralisation occurring in about one third of adults with cystic fibrosis. Bisphosphonates can increase bone mineral density and decrease the risk of new fractures in post-menopausal women and people receiving long-term oral corticosteroids. This is an updated version of a previous review.

OBJECTIVES

To assess the effects of bisphosphonates on the frequency of fractures, bone mineral density, quality of life, adverse events, trial withdrawals, and survival in people with cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Trials Register of references (identified from electronic database searches and hand searches of journals and abstract books) on 5 May 2022. We performed additional searches of PubMed, clinicaltrials.gov and the WHO ICTRP (International Clinical Trials Registry Platform) on 5 May 2022.

SELECTION CRITERIA

Randomised controlled trials of at least six months duration studying bisphosphonates in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Authors independently selected trials, extracted data and assessed risk of bias in included studies. Trial investigators were contacted to obtain missing data. We judged the certainty of the evidence using GRADE.

MAIN RESULTS

We included nine trials with a total of 385 participants (272 adults and 113 children (aged five to 18 years)). Trial durations ranged from six months to two years. Only two of the studies were considered to have a low risk of bias for all the domains.  Bisphosphonates compared to control in people with cystic fibrosis who have not had a lung transplant Seven trials included only adult participants without lung transplants, one trial included both adults and children without lung transplantation (total of 238 adults and 113 children). We analysed adults (n = 238) and children (n = 113) separately. Adults Three trials assessed intravenous bisphosphonates (one assessed pamidronate and two assessed zoledronate) and five trials assessed oral bisphosphonates (one assessed risedronate and four assessed alendronate). Bisphosphonates were compared to either placebo or calcium (with or without additional vitamin D). Data showed no difference between treatment or control groups in new vertebral fractures at 12 months (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.02 to 2.09; 5 trials, 142 participants; very low-certainty evidence) and two trials (44 participants) reported no vertebral fractures at 24 months. There was no difference in non-vertebral fractures at 12 months (OR 2.11, 95% CI 0.18 to 25.35; 4 trials, 95 participants; very low-certainty evidence) and again two trials (44 participants) reported no non-vertebral fractures at 24 months. There was no difference in total fractures between groups at 12 months (OR 0.57, 95% CI 0.13 to 2.50; 5 trials, 142 participants) and no fractures were reported in two trials (44 participants) at 24 months. At 12 months, bisphosphonates may increase bone mineral density at the lumbar spine (mean difference (MD) 6.31, 95% CI 5.39 to 7.22; 6 trials, 171 participants; low-certainty evidence) and at the hip or femur (MD 4.41, 95% 3.44 to 5.37; 5 trials, 155 participants; low-certainty evidence). There was no clear difference in quality of life scores at 12 months (1 trial, 47 participants; low-certainty evidence), but bisphosphonates probably led to more adverse events (bone pain) at 12 months (OR 8.49, 95% CI 3.20 to 22.56; 7 trials, 206 participants; moderate-certainty evidence). Children The single trial in 113 children compared oral alendronate to placebo. We graded all evidence as low certainty. At 12 months we found no difference between treatment and placebo in new vertebral fractures (OR 0.32, 95% CI 0.03 to 3.13; 1 trial, 113 participants) and non-vertebral fractures (OR 0.19, 95% CI 0.01 to 4.04; 1 trial, 113 participants). There was also no difference in total fractures (OR 0.18, 95% CI 0.02 to 1.61; 1 trial, 113 participants). Bisphosphonates may increase bone mineral density at the lumbar spine at 12 months (MD 14.50, 95% CI 12.91 to 16.09). There was no difference in bone or muscle pain (MD 3.00, 95% CI 0.12 to 75.22), fever (MD 3.00, 95% CI 0.12 to 75.22) or gastrointestinal adverse events (OR 0.67, 95% CI 0.20 to 2.26). The trial did not measure bone mineral density at the hip/femur or report on quality of life.  Bisphosphonates compared to control in people with cystic fibrosis who have had a lung transplant One trial of 34 adults who had undergone lung transplantation compared intravenous pamidronate to no bisphosphonate treatment. It did not report at 12 months and we report the 24-month data (not assessed by GRADE). There was no difference in the number of fractures, either vertebral or non-vertebral. However, bone mineral density increased with treatment at the lumbar spine (MD 6.20, 95% CI 4.28 to 8.12) and femur (MD 7.90, 95% CI 5.78 to 10.02). No participants in either group reported either bone pain or fever. The trial did not measure quality of life.

AUTHORS' CONCLUSIONS

Oral and intravenous bisphosphonates may increase bone mineral density in people with cystic fibrosis, but there are insufficient data to determine whether treatment reduces fractures. Severe bone pain and flu-like symptoms may occur with intravenous bisphosphonates. Before any firm conclusions can be drawn, trials in larger populations, including children, and of longer duration are needed to determine effects on fracture rate and survival. Additional trials are needed to determine if bone pain is more common or severe (or both) with the more potent zoledronate and if corticosteroids can ameliorate or prevent these adverse events. Future trials should also assess gastrointestinal adverse effects associated with oral bisphosphonates.

Evaluation of anthropometry as an alternative to DXA as predictor of low bone mineral density in children and adolescents with cystic fibrosis

BACKGROUND & AIMS

Low bone mineral density (BMD) for age in people with Cystic Fibrosis (CF) is associated with worse nutritional status. The aim of this study is to assess body composition by anthropometry as a predictor of BMD in people with CF.

METHODS

Multicenter cross-sectional study with 39 people aged 5 and 20 years with CF. BMD was assessed by dual energy x-ray emission (DXA) in the incidence of the total body less head (TBLH) and the TBLH Z-score (Z-TBLH) was calculated, adjusted by sex, age, height and ethnicity. Anthropometry was assessed by weight, height, mid-upper arm circumference (MUAC) and triceps skinfold (TSF). Arm muscle area (AMA) and Body Mass Index (BMI) were calculated. Lean mass (LM), fat mass (FM) and free-fat mass (FFM) were identified by DXA. The molecular analysis method by sequencing was used to identify and classify the participants regarding the presence of the F508del pathogenic variant of the CFTR gene. Statistical models of simple and multiple linear regression were created to establish the predictive power of Z-TBLH in the variables.

RESULTS

Average age of the participants was 13.31 ± 3.86 years, 59% of whom were male. They showed more LM (30.97 Kg ± 11.29) than females (23 Kg ± 6.73). 20 of 30 participants (66.7%) had at least copy of F508del. Among the multiple models, adjusted by height, age and sex, it found BMI (R² = 0.367), Weight (R² = 0.220), AMA (R² = 0.338) as significant predictors of Z-TBLH. The final model composed of AMA, TSF and Age (p = 0.001; R² = 0.381) had AMA and Age as significant predictors. AMA was associated with an increase in the BMD Z-score in the participants studied. 66.7% of genetically tested participants had the F508del pathogenic variant. The presence of the F508del variant was associated with worse nutritional status.

CONCLUSION

A statistical model composed of the values of AMA, TSF and Age can predict Z-TBLH, as well as anthropometric variables Weight, or BMI, or AMA associated with height, age and sex, in children and adolescents aged 5-20 years old, of both sexes. Anthropometric markers, as they are easy and relatively inexpensive to obtain, it is a promising alternative to the use of DXA in predicting BMD in these people with CF.

The clinical features that contribute to poor bone health in young Australians living with cystic fibrosis: A recommendation for BMD screening

BACKGROUND

For Australians living with cystic fibrosis (CF), increased longevity means greater consideration needs to be given to long-term endocrine sequelae such as CF-related bone disease. Deficits in bone mass accrual are most likely to occur during childhood and adolescence. Current guidelines in Australia suggest repeat dual-energy X-ray absorptiometry (DXA) scans every 2 years. This study aims to stratify clinical factors that determine future bone health in the Australian CF population and use this to guide a more streamlined approach to bone health screening.

METHODS

This study was a retrospective audit of all patients diagnosed with CF who were treated at the Royal Children's Hospital Melbourne, Australia from 2000 to 2016 (n = 453). Two hundred and two patients had a DXA scan in the study period (191 with height-adjusted data) and 111 patients had more than one scan (108 with height-adjusted data). An investigation into the associations between bone mineral density (BMD) Z score and potential risk factors was conducted using DXA and historical data.

RESULTS

The main predictor of future BMD was the previous BMD Z score (p < .001). Other factors found to be determinants of BMD included nutritional status, lung function (FEV₁ ), age, history of previous fracture, oral corticosteroid use, and the number of hospital admissions. However, after adjusting for previous BMD, evidence of an association remained only with nutritional status, FEV₁ , and number of hospital admissions.

CONCLUSION

Second yearly scans may be unnecessary in children with an adequate DXA score on the initial scan who remain clinically stable. However, clinical deterioration in those whose BMD was previously normal, may require closer monitoring of bone health. We propose a guideline for the frequency of DXA monitoring in relation to clinical risk factors.

Understanding the interplay between factors that influence bone mineral density in CF

BACKGROUND AND OBJECTIVES

Multiple factors affect bone mineral density (BMD) in cystic fibrosis (CF). Our aim was to perform comprehensive analyses of parameters potentially contributing to BMD.

METHODS

A prospective single-center study assessing BMD, and correlations with multiple parameters including pancreatic status, lung functions, 6-minute walk test (6MWT), clinical score (modified Shwachman-Kulczycki [SK] score), vitamin D, nutritional intake, hand grip strength (HGS), habitual physical activity (smart watches), and quality of life (SF-36 questionnaire).

RESULTS

Forty CF patients, mean age 18.3 ± 8.1 years, forced expiratory volume in 1 second 74.7% ± 17.9% predicted. Fifteen (37.5%) and 11 (27.5%) had osteopenia and osteoporosis, respectively. BMD was similar in pancreatic sufficient (pancreatic sufficient [PS], n = 15) and insufficient (pancreatic insufficient [PI], n = 25); median hip z score -1.5 ((-2.7)-(+0.2)) vs -1.5 ((-3.5)-(+0.7)), P = .79; spine -0.8 ((-2.2)-(+2)) vs -1.2 ((-4.4)-(+1.5)), P = .39 in PS vs PI, respectively. BMD correlated with HGS (r = .72, P < .001 hip; r = .52, P = .001 spine) and fat-free mass index (r = .81, P < .001 hip; r = .63, P < .001 spine). BMD z score correlated weakly with SK score and moderately with SF-36 general health. Data from smart watches, nutrition questionnaires, and 6MWT did not correlate with BMD. In a multivariate model, age and SK score predicted spine z score BMD.

CONCLUSIONS

A substantial number of CF patients have low BMD. Similar rates in PS and PI suggest that other factors, such as disease severity, may contribute to low BMD. SK and age, which can easily be obtained even with limited resources, were the best predictors of low BMD. Further larger multicenter studies are warranted to evaluate the contribution of multifactorial etiologies to low BMD in CF.

Cystic Fibrosis-related Liver Disease is Associated With Increased Disease Burden and Endocrine Comorbidities

BACKGROUND

Cystic fibrosis-related liver disease (CFLD) is the leading nonpulmonary cause of mortality in cystic fibrosis (CF). We evaluated and compared the burden of disease and nonrespiratory comorbidities of those with severe CFLD and those without (noCFLD).

METHODS

A retrospective nationwide (Australia) longitudinal review (from 1998 to 2016) of severe CFLD patients compared with noCFLD controls (matched 1 : 1 for age, genotype, pancreatic insufficiency, and center).

RESULTS

One hundred sixty-six patients with severe CFLD and 166 with noCFLD were identified. Forced expiratory volume in 1 second percentage of predicted (FEV1%) was significantly lower in CFLD than noCFLD across all ages (estimate [SE] -6.05% [2.12]; P = 0.004). Median (IQR) hospitalizations per patient per year were higher in CFLD than noCFLD for: respiratory indications (0.6 [0.2-1.3] vs 0.4 [0.1-0.9]; P = 0.002); gastrointestinal indications (0.09 [0-0.2] vs 0 [0-0.05]; P < 0.001); and other indications (0.05 [0-0.2] vs 0 [0-0.1]; P = 0.03). In the CFLD cohort, there was increased use of nasogastric (12.6% vs 5.4%; OR 2.51 [95% CI 1.06-6.46]; P = 0.03) and gastrostomy nutritional supplementation (22.9% vs 13.2%; OR 1.93 [95% CI 1.05-3.63]; P = 0.03). Additionally, the CFLD cohort had a higher frequency of bone diseases, osteopenia (26.5% vs 16.8%; OR 1.77 [95%CI 1.01-3.15]; P = 0.04) and osteoporosis (16.2% vs 8.4%; OR 2.1 [95% CI 1.01-4.52]; P = 0.04), as well as CF-related diabetes (38.5% vs 19.2%; OR 2.61 [95% CI 1.55-4.47]; P = 0.001).

CONCLUSIONS

Patients with severe CFLD have greater disease burden, with higher number of hospitalizations (both respiratory and nonrespiratory indications), nutritional interventions, and are at higher risk of CF-related bone disease and diabetes.

Association of bone mineral density with lung function in a Chinese general population: the Xinxiang rural cohort study

Background

Bone mineral density (BMD) has been positively associated with lung function in patients diagnosed with respiratory diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. However, the relationship between BMD and lung function is inconsistent in the general population.

Methods

To investigate the association between BMD and lung function in a Chinese general population, a total of 1024 adults aged 40–70 years old from Qiliying (an industrial polluted exposure area) and Langgongmiao (the reference area with non-industrial pollution) were recruited and underwent BMD and spirometry tests.

Results

Both BMD and lung function levels were lower in the exposed area compared to the reference area. In addition, BMD and lung function levels were also lower in females compared to males. Both Spearman and partial correlation analyses showed that BMD was positively correlated with FVC and FEV₁. After adjusting linear regression analyses for potential confounding factors, every 0.1 g/cm² drop in BMD was associated with 53.0 mL decrease in FVC and 33.5 mL decrease in FEV₁.

Conclusions

A reduction of BMD is associated with lower lung function in a general population from China.