Prognostic scoring systems for clinical course and survival in idiopathic pulmonary fibrosis

Development and validation of a predictive equation for resting energy expenditure in Japanese patients with interstitial lung disease

BACKGROUND AND AIMS

This study developed a prediction equation for resting energy expenditure (REE) in patients with interstitial lung disease (ILD) using indirect calorimetry and examined the errors in the prediction equation.

METHODS

This study consisted of two key phases: Study 1 focused on developing the prediction equation for REE, whereas Study 2 evaluated the accuracy of this equation through validation and error analysis. In Study 1, REE was measured, and a regression model equation was created to predict REE using multiple regression analysis, with measured REE (mREE) as the dependent variable. In Study 2, a Bland-Altman analysis was conducted to examine the phylogenetic error and agreement between predicted REE (pREE) calculated from the prediction equations developed in Study 1 and mREE.

RESULTS

In Study 1, mREE was significantly associated with fat-free mass (FFM), and the prediction equation for REE was 456.988 + 22.539 × FFM. The addition error (0.4 ± 166.1, 95% confidence interval (CI): -55.8 to 56.6, P = 0.988) and proportional error (r = 0.223, P = 0.191) between mREE and pREE were not significantly different, with an agreement of 69.4%.

CONCLUSIONS

The mREE prediction equation developed in this study showed no systematic errors and exhibited higher agreement compared with existing prediction equations. The prediction equation for REE specific to patients with ILD obtained in this study has the potential for clinical application.

The economic burden of idiopathic pulmonary fibrosis in Australia: a cost of illness study

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease found mostly in elderly persons, characterized by a high symptom burden and frequent encounters with health services. This study aimed to quantify the economic burden of IPF in Australia with a focus on resource utilization and associated direct costs.

METHODS

Participants were recruited from the Australian IPF Registry (AIPFR) between August 2018 and December 2019. Data on resource utilization and costs were collected via cost diaries and linked administrative data. Clinical data were collected from the AIPFR. A "bottom up" costing methodology was utilized, and the costing was performed from a partial societal perspective focusing primarily on direct medical and non-medical costs. Costs were standardized to 2021 Australian dollars ($).

RESULTS

The average annual total direct costs per person with IPF was $31,655 (95% confidence interval (95% CI): $27,723-$35,757). Extrapolating costs based on prevalence estimates, the total annual costs in Australia are projected to be $299 million (95% CI: $262 million-$338 million). Costs were mainly driven by antifibrotic medication, hospital admissions and medications for comorbidities. Disease severity, comorbidities and antifibrotic medication all had varying impacts on resource utilization and costs.

CONCLUSION

This cost-of-illness study provides the first comprehensive assessment of IPF-related direct costs in Australia, identifies the key cost drivers and provides a framework for future health economic analyses. Additionally, it provided insight into the major cost drivers which include antifibrotic medication, hospital admissions and medications related to comorbidities. Our findings emphasize the importance of the appropriate management of comorbidities in the care of people with IPF as this was one of the main reasons for hospitalizations.

Assessment of health-related quality of life in Australian patients with idiopathic pulmonary fibrosis: a comparison of the EQ-5D-5L and the AQoL-8D

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a progressive and debilitating chronic lung disease with a high symptom burden, which has a substantial impact on health-related quality of life (HRQoL). Our study aimed to assess the suitability of the EuroQol five-dimension (EQ-5D-5L) and the Assessment of Quality of Life- eight-dimension (AQoL-8D) questionnaires in measuring HRQoL as health state utility values (HSUVs) in an Australian IPF cohort.

METHODS

Data for estimation of health state utility values (HSUVs) were collected from participants of the Australian IPF Registry (AIPFR) using self-administered surveys which included the EQ-5D-5L and the AQoL-8D. Data on lung function and disease specific HRQoL instruments were collected from the AIPFR. Performance of the two instruments was evaluated based on questionnaire practicality, agreement between the two instruments and test performance (internal and construct validity).

RESULTS

Overall completion rates for the EQ-5D-5L and AQoL-8D were 96% and 85%, respectively. Mean (median) HSUVs were 0.65 (0.70) and 0.69 (0.72) for the EQ-5D-5L and AQoL-8D, respectively. There was reasonable agreement between the two instruments based on the Bland-Altman plot mean difference (-0.04) and intraclass correlation coefficient (0.84), however there were some fundamental differences. A larger range of values was observed with the EQ-5D-5L (-0.57-1.00 vs 0.16-1.00). The EQ-5D-5L had a greater divergent sensitivity and efficacy in relation to assessing HSUVs between clinical groupings. The AQoL-8D ,however, had a higher sensitivity to measure psychosocial aspects of HRQoL in IPF.

CONCLUSION

The EQ-5D-5L demonstrated superior performance when compared to AQoL-8D in persons with IPF. This may be attributable to the high symptom burden which is physically debilitating to which the EQ-5D-5L may be more sensitive.

The impact of idiopathic pulmonary fibrosis on health state utility values: evidence from Australia

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a progressive and universally fatal lung disease, characterised by increasing fibrosis of the lung parenchyma. In this study, we aimed to quantify the health state utility values (HSUVs) for Australians with IPF and to identify the factors affecting these HSUVs.

METHODS

Participants of the Australian IPF Registry (AIPFR), with data on EuroQoL five dimension-five level (EQ-5D-5L) profiles were included. Pulmonary function tests (PFTs) were used to assess disease severity using three IPF -based classification systems. Stepwise multivariable linear regression models assessed the relationship between HSUVs and important demographic and clinical parameters.Query RESULTS: A total of 155 participants provided data for the analysis of HSUVs. For our base case, HSUVs ranged from - 0.57 to 1.00. Mean HSUVs for all participants was 0.65 (95% CI 0.61-0.70). In general, HSUVs decreased with increasing disease severity under all disease severity classification systems. Multivariable linear regression demonstrated a negative association between HSUVs, disease severity and having more than 2 comorbidities.

CONCLUSIONS

Our study has shown that EQ-5D-5L has exhibited discriminatory sensitivity for the study population. We have demonstrated that disease severity and having more than two comorbidities was associated with lower HSUVs in Australians with IPF. Our findings support early diagnosis and appropriate evidence-based treatment to slow or prevent IPF progression; and identification and treatment of associated comorbidities to potentially improve health-related quality of life in people with IPF.

Decrements of body mass index are associated with poor outcomes of idiopathic pulmonary fibrosis patients

BACKGROUND

The processes that result in progression of idiopathic pulmonary fibrosis (IPF) remain enigmatic. Moreover, the course of this disease can be highly variable and difficult to accurately predict. We hypothesized analyses of body mass index (BMI), a simple, routine clinical measure, may also have prognostic value in these patients, and might provide mechanistic insights. We investigated the associations of BMI changes with outcome, plasma adipokines, and adaptive immune activation among IPF patients.

METHODS

Data were analyzed in an IPF discovery cohort (n = 131) from the University of Pittsburgh, and findings confirmed in patients from the University of Alabama at Birmingham (n = 148). Plasma adipokines were measured by ELISA and T-cell phenotypes determined by flow cytometry.

RESULTS

Transplant-free one-year survivals in subjects with the greatest rates of BMI decrements, as percentages of initial BMI (>0.68%/month), were worse than among those with more stable BMI in both discovery (HR = 1.8, 95%CI = 1.1-3.2, p = 0.038) and replication cohorts (HR = 2.5, 95%CI = 1.2-5.2, p = 0.02), when adjusted for age, baseline BMI, and pulmonary function. BMI decrements >0.68%/month were also associated with greater mortality after later lung transplantations (HR = 4.6, 95%CI = 1.7-12.5, p = 0.003). Circulating leptin and adiponectin levels correlated with BMI, but neither adipokine was prognostic per se. BMI decrements were significantly associated with increased proportions of circulating end-differentiated (CD28null) CD4 T-cells (CD28%), a validated marker of repetitive T-cell activation and IPF prognoses.

CONCLUSIONS

IPF patients with greatest BMI decrements had worse outcomes, and this effect persisted after lung transplantation. Weight loss in these patients is a harbinger of poor prognoses, and may reflect an underlying systemic process, such as adaptive immune activation.