Influence of age on the diagnostic accuracy of soluble biomarkers for tuberculous pleural effusion: a post hoc analysis

Diagnostic accuracy of interleukin 32γ for tuberculous pleural effusion

Background

Accurate diagnosis of tuberculous pleural effusion (TPE) with biomarkers remains difficult. Interleukin 32gamma (IL-32γ) is a recently discovered proinflammatory cytokines which plays a vital role in the immune response to TPE. This study aimed to assess the diagnostic accuracy of IL-32γ for TPE, especially in different ages of patients.

Methods

Patients with a confirmed diagnosis of pleural effusion were systematically recruited from Beijing Chao-Yang Hospital between June 2019 and May 2022. The concentration of IL-32γ and interferon-gamma (IFN-γ) were evaluated in the pleural effusions with different etiology from 188 patients using enzyme-linked immunosorbent assay method. Adenosine deaminase (ADA) was determined by peroxidase method.

Results

At a threshold value of 181.56 ng/L, IL-32γ demonstrated an area under the curve (AUC) of 0.812 [95% confidence interval (CI): 0.748-0.865], with sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), positive predictive value (PPV), and negative predictive value (NPV) of 70.2%, 86.0%, 5.0, 0.4, 92.0%, and 55.7%, respectively. In elderly patients (aged >65 years), IL-32γ demonstrated an AUC of 0.984 (95% CI: 0.891-1.000). Notably, the diagnostic accuracy of IL-32γ was significantly higher than that of ADA (P=0.03) and IFN-γ (P=0.02). Similarly, the AUCs for IL-32γ combined with ADA (0.981, 95% CI: 0.886-1.000) and IL-32γ combined with IFN-γ (1.000, 95% CI: 0.920-1.000) were significantly higher than those of ADA (P=0.04) or IFN-γ (P=0.01) alone in elderly patients.

Conclusions

IL-32γ can be used as a valuable biomarker for identifying patients with TPE, especially in elderly patients aged >65 years.

Accuracy of interleukin-27 in diagnosing tuberculous pleural effusion: Age should be considered

BACKGROUND

Tuberculous pleural effusion (TPE) diagnosis still faces many difficulties and challenges. Some studies have shown that pleural interleukin -27 (IL-27) had a diagnostic potential for TPE. However, their findings are not always consistent. This study aimed to investigate the diagnostic accuracy of pleural IL-27 for TPE.

METHODS

We prospectively enrolled 211 patients with undiagnosed pleural effusion. Effusion Mycobacterium tuberculosis (Mtb) culture, Ziehl-Neelsen staining, biopsy, and response to antituberculosis therapy were used to define TPE. The pleural IL-27 levels were determined by enzyme-linked immunosorbent assay (ELISA). A receiver operating characteristic curve (ROC) with the area under the curve (AUC) was used to evaluate the diagnostic accuracy of IL-27 for TPE. In addition, we investigated the influence of age on the diagnostic performance of IL-27 by resampling patients with different upper age limits in the inclusion criteria.

RESULTS

Among the 211 enrolled participants, 33 were TPE and 178 were non-TPE. The mean concentration of IL-27 in TPE patients was significantly higher than that of non-TPE patients. The AUC of IL-27 was 0.76 (95 %CI: 0.67-0.86). At the threshold of 500 pg/mL, the sensitivity and specificity of IL-27 were 0.26 (95 %CI: 0.20-0.33) and 0.91 (95 %CI:0.76-0.97), respectively. The AUC of IL-27 is 0.84 in patients with an upper age limit of 70. Still, it decreased to 0.76 in patients with an upper age limit of 75.

CONCLUSION

Age can affect the diagnostic performance of IL-27 for TPE.

Diagnostic accuracy of pleural fluid complement C1q for tuberculous pleural effusion in elderly patients

BACKGROUND

Previous studies indicated that pleural fluid complement C1q was helpful for diagnosing tuberculous pleural effusion (TPE), but the participants in these studies were young. The diagnostic accuracy of C1q for TPE in elderly patients remains unknown. This study aimed to investigate the diagnostic accuracy of C1q for TPE in elderly patients.

METHODS

We prospectively recruited patients with undiagnosed pleural effusion who visited the Affiliated Hospital of Inner Mongolia Medical University between September 2018 and July 2021. Their C1q in pleural fluid was detected, and the diagnostic accuracy of C1q was assessed by the receiver operating characteristic (ROC) curve analysis.

RESULTS

The median ages of patients with TPE and non-TPE were 75 and 71 years, respectively. TPE patients had significantly higher C1q than non-TPE. The area under the ROC curve (AUC) of C1q was 0.67 (95 %CI: 0.51-0.82). At the threshold of 100 mg/L, C1q had a sensitivity of 0.44 (95 %CI: 0.19-0.69) and specificity of 0.79 (95 %CI: 0.71-0.86).

CONCLUSION

C1q in pleural fluid has low diagnostic accuracy for TPE in elderly patients.

Diagnostic value of effusion adenosine deaminase, γ-interferon release assay and effusion lactatedehy drogenase/effusion adenosine deaminase for tuberculous pleural effusion in patients aged 60 years and above

Background

China is experiencing rapid growth in its population of older adults, which may lead to increased susceptibility to tuberculous pleural effusion (TPE) due to age-related changes in the immune system. This study aimed to investigate the diagnostic potential of multiple biomarkers in individuals aged 60 years and above with pleural effusion.

Methods

A total of 519 adult patients from Ningbo First Hospital were included in the study, with 7 biomarkers and their ratios in serum and pleural effusion analyzed using logistic regression analysis. Effusion Adenosine Deaminase(ADA), γ-Interferon Release Assay(IGRA), and Effusion lactatedehy drogenase(LDH)/Effusion ADA were identified as valuable parameters for differentiating TPE from non-TPE, particularly in individuals aged 60 years and older.

Results

Effusion ADA, IGRA, and Effusion LDH/Effusion ADA were identified as valuable parameters for the differential diagnosis of TPE from non-TPE, showing good diagnostic performance in individuals aged 60 years and older. The combined diagnosis of these three indexes achieved the highest diagnostic accuracy for TPE in this age group, with an AUC of 0.925, sensitivity of 85.23%, and specificity of 89.57%.

Conclusions

Overall, the study highlights the importance of using multiple indicators for a combined diagnosis to improve diagnostic efficacy in detecting tuberculous pleurisy in older individuals as for young patients.

Diagnostic accuracy and cellular origin of pleural fluid CXCR3 ligands for tuberculous pleural effusion

BACKGROUND

Pleural biomarkers represent potential diagnostic tools for tuberculous pleural effusion (TPE) due to their advantages of low cost, short turnaround time, and less invasiveness. This study evaluated the diagnostic accuracy of two CXCR3 ligands, C-X-C motif chemokine ligand 9 (CXCL9) and CXCL11, for TPE. In addition, we investigated the cellular origins and biological roles of CXCL9 and CXCL11 in the development of TPE.

METHODS

This double-blind study prospectively enrolled patients with undiagnosed pleural effusion from two centers (Hohhot and Changshu) in China. Pleural fluid on admission was obtained and levels of CXCL9 and CXCL11 were measured by an enzyme-linked immunosorbent assay (ELISA). The receiver operating characteristic (ROC) curve and the decision curve analysis (DCA) were used to evaluate their diagnostic accuracy and net benefit, respectively. THP-1 cell-derived macrophages were treated with Bacillus Calmette-Guérin (BCG), and quantitative real-time PCR (qRT-PCR) and ELISA were used to determine the mRNA and protein levels of CXCL9 and CXCL11. The chemoattractant activities of CXCL9 and CXCL11 for T helper (Th) cells were analyzed by a transwell assay.

RESULTS

One hundred and fifty-three (20 TPEs and 133 non-TPEs) patients were enrolled in the Hohhot Center, and 58 (13 TPEs and 45 non-TPEs) were enrolled in the Changshu Center. In both centers, we observed increased CXCL9 and CXCL11 in TPE patients. The areas under the ROC curves (AUCs) of pleural CXCL9 and CXCL11 in the Hohhot Center were 0.70 (95 % CI: 0.55-0.85) and 0.68 (95 % CI: 0.52-0.84), respectively. In the Changshu Center, the AUCs of CXCL9 and CXCL11 were 0.96 (95 % CI: 0.92-1.00) and 0.97 (95 % CI: 0.94-1.00), respectively. The AUCs of CXCL9 and CXCL11 decreased with the advancement of age. The decision curves of CXCL9 and CXCL11 showed net benefits in both centers. CXCL9 and CXCL11 were upregulated in BCG-treated macrophages. Pleural fluid from TPE and conditioned medium from BCG-treated macrophages were chemotactic for Th cells. Anti-CXCL9 or CXCL11 neutralizing antibodies could partly block the chemotactic activity.

CONCLUSIONS

Pleural CXCL9 and CXCL11 are potential diagnostic markers for TPE, but their diagnostic accuracy is compromised in elderly patients. CXCL9 and CXCL11 can promote the migration of peripheral Th cells, thus representing a therapeutic target for the treatment of TPE.

Tuberculous pleuritis: clinical presentations and diagnostic challenges

PURPOSE OF REVIEW

Tuberculous pleuritis (TBP) is one of the most common types of extrapulmonary tuberculosis. We highlight the latest epidemiology of TBP, the heterogeneity of its presentation and the performance of different diagnostic strategies.

RECENT FINDINGS

There are differential trends in the incidences of TBP worldwide. Its incidence increased in China but decreased in the United States in the past decade. The presentation of TBP is heterogeneous regarding clinical symptoms, radiological findings and pleural fluid analysis results. Conventional microbiological tests have low sensitivities to diagnose TBP. Recent research focused on various diagnostic tools with better yield. The sensitivity of nucleic acid amplification tests (NAAT) in pleural fluid, including the latest generation of PCR and sequencing-based techniques for detecting tuberculosis, remains suboptimal. Various pleural fluid biomarkers have been explored, but there is a lack of consensus on their clinical utility and cutoff levels.

SUMMARY

The heterogeneity of clinical presentation poses obstacles to diagnosing TBP. Further development of diagnostic tools, including more robust NAAT and biomarkers with additional validation, is needed before incorporation into routine clinical practice.

Diagnostic scoring systems for tuberculous pleural effusion in patients with lymphocyte-predominant exudative pleural profile: A development study

Background

Diagnosing tuberculous pleural effusion (TPE) in patients presenting with Lymphocyte-Predominant Exudative pleural effusion (LPE) is challenging, due to the poor clinical utility of TB culture. Adenosine deaminase (ADA) has been recommended for diagnosis, but its high cost and limited availability hinder its clinical utility. We aim to develop diagnostic prediction tools for Thai patients with LPE in scenarios where pleural fluid ADA is available but yields negative results and in situations where pleural fluid ADA is not available.

Methods

Two diagnostic prediction tools were developed using retrospective data from patients with LPE at Surin Hospital. Model 1 is for ADA-negative results, and Model 2 is for situations where pleural fluid ADA testing is unavailable. The models were derived using multivariable logistic regression and presented as two clinical scoring systems: round-up and count scoring. The score cut-point that achieves a positive predictive value (PPV) comparable to the post-test probability of a pleural fluid ADA at a cut-point of 40 U/L was used as a threshold for initiating anti-TB treatment.

Results

A total of 359 patients were eligible for analysis, with 166 diagnosed with TPE and 193 diagnosed with non-TPE. Age <40 years, fever, pleural fluid protein ≥5 g/dL, male gender, pleural fluid color, and pleural fluid ADA ≥20 U/L were identified as final predictors. Both models demonstrated excellent discriminative ability (AuROC: 0.85 to 0.89). The round-up scoring demonstrated PPV above 90% at cut-off points of 4 and 4.5, while the count scoring achieved cut-off points of 3 and 4 for Model 1 (Lex-2P2A) and Model 2 (Lex-2P-MAC), respectively.

Conclusion

These diagnostic tools offer valuable assistance in differentiating between TPE and non-TPE in LPE patients with negative pleural fluid ADA (Lex-2P2A) and in settings where pleural fluid ADA testing is not available (Lex-2P-MAC). Implementing these diagnostic scores may have the potential to improve TPE diagnosis and facilitate prompt initiation of treatment.

Pleural fluid soluble Fas ligand and tuberculous pleural effusion: a prospective diagnostic test accuracy study

Background

The diagnosis of tuberculous pleural effusion (TPE) is challenging for pulmonologists. Adenosine deaminase (ADA), interferon-gamma (IFN-γ), and interleukin-27 (IL-27) have some limitations for diagnosing TPE. Soluble Fas ligand (sFasL) had a high diagnostic value for TPE. However, it remains unknown: (I) whether sFasL has an additional diagnostic value to the traditional markers (e.g., ADA); (II) whether sFasL provides a net benefit in patients with undiagnosed pleural effusion; (III) factors affecting the diagnostic accuracy of sFasL for TPE. This study aimed to evaluate the additional diagnostic value and benefit of pleural fluid sFasL for TPE.

Methods

We prospectively enrolled 211 patients with undiagnosed pleural effusion. The concentration of sFasL in pleural fluid was measured by an enzyme-linked immunosorbent assay (ELISA). The diagnostic accuracy and net benefit of sFasL and ADA for TPE were analyzed by a receiver operating characteristic (ROC) curve, decision curve analysis (DCA), net reclassification improvement (NRI), and integrated discriminant improvement (IDI).

Results

The area under the ROC curves (AUCs) of sFasL and ADA were 0.74 (95% CI: 0.65-0.83) and 0.80 (95% CI: 0.71-0.90), respectively. The decision curve of sFasL revealed net benefit. The continuous NRI and IDI of sFasL were 0.36 (0.00-0.72, P=0.05) and 0.02 (-0.01-0.06, P=0.18), respectively.

Conclusions

Pleural fluid sFasL has moderate diagnostic accuracy for TPE.

Hepatocyte growth factor combined with adenosine deaminase as biomarker for diagnosis of tuberculous pleural effusion

Background

The simple, rapid, and accurate diagnosis of tuberculous pleural effusion (TPE) remains difficult. This study aimed to determine the accuracy of hepatocyte growth factor (HGF) in the diagnosis of TPE.

Methods

We quantified the expression of HGF, adenosine deaminase (ADA), and interferon gamma (IFN-γ) in pleural effusion (PE) in 97 TPE subjects and 116 non-TPE subjects using an enzyme-linked immunosorbent assay (ELISA) or a fully automatic biochemical analyzer. The diagnostic performance of these three biomarkers was evaluated using a receiver operating characteristic (ROC) curve of subjects by age and gender.

Results

We discovered that the TPE group had much higher levels of HGF than the non-TPE group, regardless of age or gender, and that there was no statistically significant difference between the two groups' levels of HGF expression in peripheral plasma. In female TPE patients aged ≤65 years, the AUCs of TPE and non-TPE diagnosed by HGF, ADA or IFN-γ were 0.988, 0.964, and 0.827, respectively. HGF plus ADA had the highest diagnostic efficacy in female TPE patients aged ≤65 years. With HGF plus ADA having a cut-off value of 0.219 for distinguishing TPE from non-TPE, the area under the curve (AUC), sensitivity (SEN), specificity (SPE), positive predictive value (PPV), and negative predictive value (NPV) were, respectively, 0.998 (95% confidence interval [CI], 0.993-1.000), 100 (95% CI, 89.997-100.000), 96.667 (95% CI, 82.783-99.916), 97.222 (95% CI, 83.594-99.586), and 100.

Conclusion

This study confirmed that HGF plus ADA has high diagnostic efficacy in younger female TPE patients and has the potential to be an excellent biomarker.

Age affects the diagnostic accuracy of the cancer ratio for malignant pleural effusion

BACKGROUND AND OBJECTIVE

Cancer ratio (CR), which is defined as serum lactate dehydrogenase (LDH) to pleural fluid adenosine deaminase (ADA) ratio, has been reported to be a useful diagnostic marker for malignant pleural effusion (MPE). Whether its diagnostic accuracy is affected by age remains unknown. This study aimed to investigate the effects of age on the diagnostic accuracy of CR.

METHODS

The participants in this study were from a prospective cohort (SIMPLE cohort, n = 199) and a retrospective cohort (BUFF cohort, n = 158). All participants were patients with undiagnosed pleural effusion (PE). We used receiver operating characteristic (ROC) curves to evaluate the diagnostic accuracy of CR. The effect of age on the diagnostic accuracy of CR was investigated by adjusting the upper limit of age for participant enrolment.

RESULTS

Eighty-eight MPE patients were verified in the SIMPLE cohort, and thirty-five MPE patients were verified in the BUFF cohort. The AUCs of CR in the SIMPLE and BUFF cohorts were 0.60 (95% CI: 0.52-0.68) and 0.63 (95% CI: 0.54-0.71), respectively. In both cohorts, the AUCs of CR decreased with the advancement of age.

CONCLUSION

Age can affect the diagnostic accuracy of CR for MPE. CR has limited diagnostic value in older patients.

KEY MESSAGE

Cancer ratio is a promising diagnostic marker for malignant pleural effusion. This study revealed that its diagnostic accuracy decreased in older patients. Its diagnostic accuracy is overestimated by previous studies using tuberculosis and pneumonia patients as controls.

Expert Review on Contemporary Management of Common Benign Pleural Effusions

Heart failure (HF) and cirrhosis are frequently associated with pleural effusions (PEs). Despite their apparently benign nature, both HF-related effusions and hepatic hydrothorax (HH) have poor prognosis because they represent an advanced stage of the disease. Optimization of medical therapy in these two entities involve not only the use of diuretics, but also other pharmacological therapies. For instance, all HF patients with reduced or mildly reduced left ventricular ejection fraction can benefit from angiotensin receptor-neprilysin inhibitors, beta blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors. Conversely, it is better for HH patients to avoid nonselective beta blockers. Refractory cardiac- and cirrhosis-related PEs are commonly managed by iterative therapeutic thoracentesis. When repeated aspirations are needed, thereby diminishing quality of life, the insertion of an indwelling pleural catheter (IPC) may be warranted. However, in selected HH patients who are diuretic-resistant or diuretic-intractable, placement of transjugular intrahepatic portosystemic shunts should be considered as a bridge to liver transplantation, whereas in transplant candidates the role of IPC is debatable. Another benign condition, pleural tuberculosis (TB) is a serious health problem in developing countries. Diagnostic certainty is still a concern due to the paucibacillary nature of the infection, although the use of more sensitive nucleic acid amplification tests is becoming more widespread. Its treatment is the same as that of pulmonary TB, but the potential drug interactions between antiretroviral and anti-TB drugs in HIV-coinfected patients as well as the current recommended guidelines for the different types of anti-TB drugs resistance should be followed.

Application of Adenosine Deaminase and γ-Interferon Release Assay in Pleural Fluid for the Diagnosis of Tuberculous Pleural Effusion in Patients Over 40 Years Old

Background

In patients with tuberculous pleural effusion (TPE) of various ages, the diagnostic accuracy of pleural biomarkers varies, and there are insufficient studies specifically in different age groups. Therefore, we investigated the adenosine deaminase cut-off value and its combination with the gamma interferon release assay for the diagnosis of TPE among patients aged ≥40 years.

Methods

A retrospective analysis of 198 patients who underwent medical thoracoscopy and were admitted to the hospital between 2015 and 2020 with exudative pleural effusion and either fever, night sweats, fatigue, cough, or other clinical manifestations was performed. The medical thoracoscopy, ADA, and T-SPOT results were analysed in the pleural fluid. The patients were divided into groups based on age: 18-39, 40-59, and 60-87.

Results

The best cut-off values of ADA were 29.5, 31.5 and 19.5 U/L, respectively, for the aged 18-39, aged 40-87 and aged 60-87 groups. The accuracy of 31.5 U/L was higher than 40 U/L for aged ≥40 years (86 vs 83%). The ADA diagnostic accuracy was higher than that of people under 40 years (83 vs 77%) when cut-off value of ADA was 40 U/L, but the IGRA accuracy was lower than that of people under 40 (87 vs 91%). The sensitivity of ADA or IGRA detection in patients over 40 years was 99%, and the specificity was 78%. The ADA specificity combined with IGRA for TPE was the highest (100%) in the ≥40 age group, and the sensitivity was 69%.

Conclusion

Our study revealed the best cut-off values of ADA for TBE in different age groups. Combining ADA and IGRA in pleural fluid improves the detection rate of TPE in patients over 40 years of age with exudative pleural effusion. ADA combined with IGRA increases specificity, and ADA or IGRA increases sensitivity substantially.

Diagnostic accuracy of pleural fluid lactate dehydrogenase to adenosine deaminase ratio for tuberculous pleural effusion: an analysis of two cohorts

Background

This study aimed to evaluate the diagnostic accuracy of pleural fluid (PF) lactate dehydrogenase (LDH) to adenosine deaminase (ADA) (LDH/ADA) ratio for tuberculous pleural effusion (TPE). Especially to explore whether the LDH/ADA ratio provides added diagnostic value to ADA.

Methods

The diagnostic accuracy of PF LDH/ADA ratio and ADA for TPE was evaluated in two cohorts, named the BUFF (Biomarkers for patients with Undiagnosed pleural eFFusion) cohort (62 with TPE and 194 with non-TPE) and the SIMPLE (a Study Investigating Markers in PLeural Effusion) cohort (33 with TPE and 177 with non-TPE). Receiver operating characteristic (ROC) curve and decision curve were used to measure the diagnostic accuracy of the PF LDH/ADA ratio. The added diagnostic value of the LDH/ADA ratio to ADA was evaluated with net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

Results

The area under the ROC curves (AUCs) of PF ADA and LDH/ADA ratio in the BUFF cohort were 0.76 and 0.74, respectively. In the SIMPLE cohort, the AUCs of PF ADA and LDH/ADA ratio were 0.80 and 0.85, respectively. The decision curves of PF LDH/ADA and ADA were close in both the BUFF and SIMPLE cohorts. The NRI and IDI analyses did not reveal any added diagnostic value of LDH/ADA to ADA.

Conclusions

PF LDH/ADA ratio has moderate diagnostic accuracy for TPE. It does not provide added diagnostic value beyond ADA. The current evidence does not support LDH/ADA ratio for diagnosing TPE.

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

Complement Component C1q as an Emerging Biomarker for the Diagnosis of Tuberculous Pleural Effusion

Background and Objective: The accurate differential diagnosis of tuberculous pleural effusion (TPE) from other exudative pleural effusions is often challenging. We aimed to validate the accuracy of complement component C1q in pleural fluid (PF) in diagnosing TPE. Methods: The level of C1q protein in the PF from 49 patients with TPE and 61 patients with non-tuberculous pleural effusion (non-TPE) was quantified by enzyme-linked immunosorbent assay, and the diagnostic performance was assessed by receiver operating characteristic (ROC) curves based on the age and gender of the patients. Results: The statistics showed that C1q could accurately diagnose TPE. Regardless of age and gender, with a cutoff of 6,883.9 ng/mL, the area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of C1q for discriminating TPE were 0.898 (95% confidence interval: 0.825-0.947), 91.8 (80.4-97.7), 80.3 (68.2-89.4), 78.9 (69.2-86.2), and 92.5 (82.6-96.9), respectively. In subgroup analysis, the greatest diagnostic accuracy was achieved in the younger group (≤ 50 years of age) with an AUC of 0.981 (95% confidence interval: 0.899-0.999) at the cutoff of 6,098.0 ng/mL. The sensitivity, specificity, PLR, NLR, PPV, and NPV of C1q were 95.0 (83.1-99.4), 92.3 (64.0-99.8), 97.4 (85.2-99.6), and 85.7 (60.6-95.9), respectively. Conclusion: Complement component C1q protein was validated by this study to be a promising biomarker for diagnosing TPE with high diagnostic accuracy, especially among younger patients.