What is the correlation between changes in Hospital Anxiety and Depression Scale (HADS) scores and changes in 6-Minute Walk Test (6MWT) distance and modified Medical Research Council (mMRC) dyspnea scale in patients with chronic respiratory disease before and after pulmonary rehabilitation?

Correlation Between HADS Scores and Functional Measures in Chronic Respiratory Disease Patients Undergoing Pulmonary Rehabilitation

There is a significant inverse correlation between anxiety and depression symptoms (measured by HADS) and functional performance (measured by 6MWT distance), with improvements in psychological symptoms after pulmonary rehabilitation being associated with greater improvements in exercise capacity and reduced dyspnea.

Relationship Between Psychological Symptoms and Functional Measures

Baseline Correlations

• Patients with chronic respiratory diseases who have higher anxiety and depression scores on HADS demonstrate:

  • Significantly worse functional capacity measured by 6MWT distance 1
  • Higher levels of dyspnea on the mMRC scale 2
  • Poorer health-related quality of life 3

• The National Emphysema Treatment Trial found that anxiety and depression were associated with significantly worse functional capacity as measured by 6-minute walk distance and maximal exercise capacity 2

• In the ECLIPSE study, patients with COPD with poor 6MWD had:

  • Worse SGRQ-C activity scores
  • Higher percentage of dyspnea symptoms (mMRC > 2)
  • More depressive symptoms 2

Magnitude of Correlation

• Patients with high anxiety show significantly poorer functional performance:

  • 6MWT distance of 308.75 ± 120.16 m in high anxiety group vs. 373.76 ± 106.56 m in no anxiety group (p < 0.01) 1

• Multivariate analysis shows that anxiety and depression account for approximately 33% of the variance in functional performance, even after controlling for COPD severity 1

Changes After Pulmonary Rehabilitation

Impact on Psychological Symptoms

• Pulmonary rehabilitation significantly reduces anxiety and depression symptoms:

  • Abnormal anxiety scores decrease from 25% to 9% after PR
  • Abnormal depression scores decrease from 17% to 6% after PR 4

• Among patients with abnormal baseline scores who complete PR:

  • 91% of those with abnormal anxiety scores exceed the minimal clinically important difference (MCID)
  • 93% of those with abnormal depression scores exceed the MCID 4

Correlation Between Psychological and Functional Improvements

• Patients who respond to PR with improved 6MWT distance (≥30m improvement) show:

  • Better oxygen uptake
  • Improved ventilation rate
  • Greater overall functional capacity 5

• Patients who fail to improve in 6MWT after PR:

  • Are more likely to have IPF diagnosis
  • Experience greater arterial oxygen desaturation during exercise
  • Show less improvement in gas exchange parameters 5

• Patients with higher levels of anxiety and depression at baseline:

  • May fail to reach minimal clinically important difference in 6MWT post-intervention 6
  • Can still achieve significant improvements in disease impact outcomes 6

Clinical Implications

Screening and Assessment

• All patients with chronic respiratory disease should be screened for anxiety and depression before starting pulmonary rehabilitation 1

• The Hospital Anxiety and Depression Scale (HADS) is an effective screening tool:

  • Scores ≥10 indicate abnormal anxiety or depression
  • A change of ≥1.5 units is considered clinically meaningful 4

Predictors of Response

• Factors associated with anxiety and depression in chronic respiratory patients include:

  • Younger age
  • Female sex
  • Higher education level
  • Lower household income
  • History of smoking 3

• Patients with abnormal anxiety and depression scores are less likely to complete pulmonary rehabilitation programs 4

Treatment Considerations

• Comprehensive pulmonary rehabilitation should include:

  • Exercise training
  • Stress management education
  • Psychosocial support 2

• Patients with higher baseline anxiety and depression may require:

  • More intensive psychological support
  • Longer duration of pulmonary rehabilitation
  • Additional interventions to maximize functional outcomes 6

Pitfalls and Caveats

• Anxiety and panic can lead to alterations in breathing pattern that may result in severe progressive dynamic hyperinflation, potentially precipitating emergency department visits or respiratory failure 2

• The presence of depressive or anxious symptoms does not necessarily indicate a depressive or anxiety disorder according to DSM criteria; proper screening is essential 2

• Untreated major depression or anxiety disorders may impact participation in and reduce benefits from pulmonary rehabilitation 2

• Patients with IPF and greater exercise-induced hypoxemia may be less responsive to standard pulmonary rehabilitation protocols and may require alternative exercise regimens 5