Independent Predictors Of 6MWD Research Articles

Heart Rate Response Predicts 6-Minutes Walking Distance in Pulmonary Arterial Hypertension

Because the 6-minute walking test (6MWT) is a self-paced submaximal test, the 6-minute walking distance (6MWD) is substantially influenced by individual effort level and physical condition, which is difficult to quantify. We aimed to explore the optimal indicator reflecting the perceived effort level during 6MWT. We prospectively enrolled 76 patients with pulmonary arterial hypertension and 152 healthy participants; they performed 2 6MWTs at 2 different speeds: (1) at leisurely speed, as performed in daily life without extra effort (leisure 6MWT) and (2) an increased walking speed, walking as the guideline indicated (standard 6MWT). The factors associated with 6MWD during standard 6MWT were investigated using a multiple linear regression analysis. The heart rate (HR) and Borg score increased and oxygen saturation (SpO2) decreased after walking in 2 6MWTs in both groups (all p <0.001). The ratio of difference in HR before and after each test (ΔHR) to HR before walking (HRat rest) and the difference in SpO2 (ΔSpO2) and Borg (ΔBorg) before and after each test were all significantly higher in both groups after standard 6MWT than after leisure 6MWT (all p <0.001). Multiple linear regression analysis revealed that ΔHR/HRat rest was an independent predictor of 6MWD during standard 6MWT in both groups (both p <0.001, adjusted R2=0.737 and 0.49, respectively). 6MWD and ΔHR/HRat rest were significantly lower in patients than in healthy participants (both p <0.001) and in patients with cardiac functional class III than in patients with class I/II (both p <0.001). In conclusion, ΔHR/HRat rest is a good reflector of combined physical and effort factors. HR response should be incorporated into 6MWD to better assess a participant's exercise capacity.

Correlation of Echocardiographic Variables with Exercise Capacity in Patients with Pulmonary Hypertension due to Congenital Heart Diseases

Abstract Background Pulmonary arterial hypertension (PAH) is a disease of the pulmonary circulation with resultant effects on the right heart. Conceptually, left heart anatomy and function should be normal in patients with PAH. However, the RV and left ventricle (LV) do not function in isolation, sharing a common pericardial sac and inter-ventricular septum which in turn refers to the significance of assessment of both ventricles which has implications for patient prognosis with PAH. Aim Study the correlation between echocardiographic hemodynamic parameters and functional capacity in patients with pulmonary hypertension due to congenital heart disease and detection which parameter is the most independent predictor of functional capacity in patients with PAH-CHD. Methodology The study was conducted in the period from November 2016 to September 2017 including 34 patients who had been diagnosed with pulmonary arterial hypertension associated with congenital heart diseases (PAH-CHD). All of them were recruited from the congenital heart diseases unit at Ain Shams University hospital. The studied group was divided into two groups in a cross-sectional study: Group I: This included 21 patients with functional capacity according the 6MWT less than 330 m as an average for all subjects. Group II: This included 13 patients with functional capacity more than 330 m. Patients’ participation was voluntary and the subject had the right to withdraw from the study at any time without affecting his/her further medical care. Results The whole study population was divided according to the 6MW distance into two groups less than 330 and more than or equal 330 m. Comparing the 6MWD of each patient with the different Echocardiographic variables of systolic &amp; diastolic dysfunction revealed that the group of shorter 6MW distance had higher RVSP, MPAP, E/e’ ratio, LVMPI and RVMPI, while they had lower LV e’ TDI, LV GRS, RV FAC and RV GLS (less negative value). Multivariate analysis of these Echocardiographic variables revealed that MPAP is independent predictor of 6MWD &amp; thus an independent predictor of functional capacity in PAH-CHD patients. Conclusion Assessment of RV and LV function in PAH-CHD patients is important. Strain measurement by STE provides valuable information on the quantitative RV and LV functional assessment in the setting of volume and pressure overload. The MPAP and saturation were found to be the most independent predictors affecting the functional capacity of the patients with PAH-CHD. Recommendations Assessment of functional capacity in patients with PH using the 6MWT is recommended as a routine investigation from diagnosis and during follow-up and correlated with the echocardiographic variables, it has been shown to be practical and feasible and provides an easy and not expensive tool for clinical and prognostic assessment.

Estimated Glomerular Filtration Rate and 6-Minute Walk Distance in African Americans with Mild to Moderate Heart Failure

Background/Aims: The 6-minute walk test is a measure of functional capacity in patients with heart failure (HF) or chronic kidney disease (CKD). The association between estimated glomerular filtration rate (eGFR) and 6-minute walk distance (6MWD) has not been investigated in African-Americans (AA), despite them having a higher incidence of CKD and chronic HF. Thus, our aim was to determine if eGFR was an independent predictor of 6MWD in AA >50 years of age with HF. Methods: In this cross-sectional study, we examined the relationship between eGFR and 6MWD in 45 AA patients with HF from an urban outpatient HF clinic, using logistic regression with bootstrapping. Results: The sample consisted of 53% females; mean age = 64.8 ± 9 years, mean eGFR = 61.6 ± 20 mL/min/1.73 m², and mean 6MWD = 222 ± 78 m. A decrease in eGFR by 10 mL/min/1.73 m² was associated with 46% higher odds (p = 0.02) of a 6MWD ≤200 m in an unadjusted model and 39-41% higher odds (p = 0.03) of a 6MWD ≤200 m in adjusted models. Conclusion: A decrease in eGFR significantly predicted a shorter 6MWD in AA patients with HF. Therefore, a reduction in eGFR may be used as an early marker to identify and manage declining functional capacity in these patients.

Reference Equation for Six Minute Walk Test in Healthy Western India Population.

The Six Minute Walk Test (6MWT) is used to assess disease progression and survival in chronic cardiopulmonary disorders. However, variability is noted in the six minute walk test distance (6MWD) in different populations. We aimed to develop a reference equation for 6MWD in healthy Western India population and compare the results with previously published Indian and Caucasian reference equations. Total 174 healthy subjects between 25 to 75 years performed the 6MWT. Variables assessed were age, height, weight, body mass index and sex. Predicted equations were derived using multiple linear regression and compared with the equations for North Indian male, South Indian and Caucasian population using Bland - Altman method. The 6MWD mean (SD) was 512.38 (67.84) m for men and 457.27 (56.75) m for women with p=0.001. The 6MWD correlated with age (r=-0.44), height (r=0.43), weight (r=0.21) in univariate analysis. Stepwise multiple regression analysis showed age and sex to be independent predictors of 6MWD, R(2) =0.307. The reference equation for healthy Western India population is 553.289 + (-2.11 x age) + (45.323 x sex; men=1 and women =0). Bland Altman analysis showed that the mean bias was 50.87m (95% limits of agreement 134.77 to - 33.0) for North Indian male equation, 50.75m (95% limits of agreement 105.72 to - 4.22) for South Indian equation and 122.72m (95%limits of agreement 254.11 to - 8.67) for Enright and Sherrill's equation. The North Indian male, South Indian and Caucasian equations significantly over-estimated the predicted walk distance for our healthy population. Hence, there is a need to develop subgroup population specific reference equations.

Predictors of Functional Capacity in Chronic Heart Failure: Echocardiography Versus Six-Minute Walk Test

Background: Six-minute walk test (6MWT) constitutes a suitable alternative for Cardio-pulmonary exercise testing to assess functional capacity in patients with heart failure (HF). Echocardiography has always been considered as the most useful easy test for evaluation of these patients. Purpose: To determine the echocardiographic predictors of six-minute walk distance (6MWD) in patients with chronic systolic heart failure as an objective assessment of functional capacity. Patients: This study included 40 patients with HF (EF <40%) presenting to Ain Shams University hospital heart failure clinic with grade I to II NYHA (New York Heart Association) classification. All performed simultaneous transthoracic echocardiographic study and 6MWT. Results: The mean 6MWD was 340.25 ± 88.64 meters. 26 patients (65%) walked more than 300 meters (group I) while 35% (14 patients) did not (group II). Right ventricular systolic pressure (RVSP) and E/e’ were significantly higher in (group II), (p=0.04 and 0.05 respectively). There were significant negative correlations between 6MWD and each of LVESV (r=-0.34, p=0.03), E/e’(r=-0.36, p=0.02) and, RVSP (r=-0.34, p=0.03). Linear regression analysis showed RVSP as the only independent predictor of 6MWD, thus an independent predictor of functional capacity in HF patients. Further more this study suggested a predictive model of estimation of 6MWD from a given value of RVSP: 6MWD = a + (b x RVSP); (a and b are constants) with a standard error of ±42 m. Conclusion: RVSP, LVESV and E/e’ were correlated with 6MWD in chronic HF patients. Among different echocardiographic parameters, RVSP can be used as an independent predictor of functional capacity in HF patients. Further studies are still needed to ascertain the sensitivity and specificity of this model in prediction of functional capacity in HF patients in everyday practice.

Six-minute walk test in Chinese adults with clinically stable bronchiectasis: association with clinical indices and determinants

Background:The profiles of 6-minute walk distance (6MWD) in adults with clinically stable bronchiectasis in Chinese adult patients with bronchiectasis are unclear.Objectives:To delineate the 6MWD by stratification of clinical indices, and to investigate the factors associated with reduced 6MWD in Chinese adults with clinically stable bronchiectasis.Methods:We recruited 141 adult bronchiectasis patients (mean age: 44.3 ± 13.9 years). Demography, radiology, spirometry, diffusing capacity, etiology, sputum bacteriology, modified Medical Research Council dyspnea scale (MMRC) and quality of life were assessed. The safety profile of the measurement was also examined.Results:Lower levels of 6MWD were associated with older age (>50 years), higher HRCT total score, presence of cystic bronchiectasis, bilateral bronchiectasis, reduced diffusing capacity, higher MMRC score, and higher SGRQ scores. Correlation coefficients between 6MWD and spirometry and quality of life scores were different in patients with 6MWD higher and lower than lower limit of normal. DLCO being less than 80% predicted (OR = 3.13, 95% CI: 1.32–7.43, P = 0.01) and MMRC scale between 1 and 4 (OR = 6.42, 95% CI: 2.27–18.18, P < 0.01) were the factors associated with 6MWD being less than the lower limit of normal (80% predicted value). No severe adverse events were reported.Conclusion:The 6MWD could be safely measured in adult patients with bronchiectasis and is poorly associated with clinical parameters. DLCO less than 80% predicted and higher MMRC scale are independent predictors of 6MWD below the lower limit of normal. Our findings will provide a reference for management of bronchiectasis patients in mainland China.

Left ventricular diastolic dysfunction in pulmonary hypertension predicts functional capacity and clinical worsening: a tissue phase mapping study.

BackgroundThe function of the right and left ventricles is intimately related through a shared septum and pericardium. Therefore, right ventricular (RV) disease in pulmonary hypertension (PH) can result in abnormal left ventricular (LV) myocardial mechanics. To assess this, we implemented novel cardiovascular magnetic resonance (CMR) tissue phase mapping (TPM) to assess radial, longitudinal and tangential LV myocardial velocities in patients with PH.MethodsRespiratory self-gated TPM was performed using a rotating golden-angle spiral acquisition with retrospective cardiac gating. TPM of a mid ventricular slice was acquired in 40 PH patients and 20 age- and sex-matched healthy controls. Endocardial and epicardial LV borders were manually defined, and myocardial velocities calculated using in-house software. Patients without proximal CTEPH (chronic thromboembolic PH) and not receiving intravenous prostacyclin therapy (n = 34) were followed up until the primary outcome of disease progression (death, transplantation, or progression to intravenous therapy) or the end of the study. Physicians who determined disease progression were blinded to CMR data. Conventional ventricular volumetric indices and novel TPM metrics were analyzed for prediction of 6-min walk distance (6MWD) and disease progression.ResultsPeak longitudinal (p < 0.0001) and radial (p = 0.001) early diastolic (E) wave velocities were significantly lower in PH patients compared with healthy volunteers. Reversal of tangential E waves was observed in all patients and was highly discriminative for the presence of PH (p < 0.0001).The global radial E wave (β = 0.41, p = 0.017) and lateral wall radial systolic (S) wave velocities (β = 0.33, p = 0.028) were the only independent predictors of 6MWD in a model including RV ejection fraction (RVEF) and LV stroke volume.Over a median follow-up period of 20 months (IQR 7.9 months), 8 patients commenced intravenous therapy and 1 died. Global longitudinal E wave was the only independent predictor of clinical worsening (6.3× increased risk, p = 0.009) in a model including RVEF and septal curvature.ConclusionsTPM metrics of LV diastolic function are significantly abnormal in PH. More importantly, abnormal LV E wave velocities are the only independent predictors of functional capacity and clinical worsening in a model that includes conventional metrics of biventricular function.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-015-0220-3) contains supplementary material, which is available to authorized users.

Echocardiographic predictors of exercise capacity and mortality in chronic obstructive pulmonary disease.

BackgroundChronic obstructive pulmonary disease (COPD) reduces exercise capacity, but lung function parameters do not fully explain functional class and lung-heart interaction could be the explanation. We evaluated echocardiographic predictors of mortality and six minutes walking distance (6MWD), a marker for quality of life and mortality in COPD.MethodsNinety COPD patients (GOLD criteria) were evaluated by body plethysmography, 6MWD and advanced echocardiography parameters (pulsed wave tissue Doppler and speckle tracking).ResultsMean 6MWD was 403 (± 113) meters. All 90 subjects had preserved left ventricular (LV) ejection fraction 64.3% ± 8.6%. Stroke volume decreased while heart rate increased with COPD severity and hyperinflation. In 66% of patients, some degree of diastolic dysfunction was present. Mitral tissue Doppler data in COPD could be interpreted as a sign of low LV preload and not necessarily an intrinsic impairment in LV relaxation/compliance. Tricuspid regurgitation (TR) increased with COPD severity and hyperinflation. Age (p < 0.001), BMI (p < 0.001), DLCO SB (p < 0.001) and TR (p 0.005) were independent predictors of 6MWD and a multivariable model incorporating heart function parameters (adjusted r2 = .511) compared well to a model with lung function parameters alone (adjusted r2 = .475). LV global longitudinal strain (p = 0.034) was the only independent predictor of mortality among all baseline, body plethysmographic and echocardiographic variables.ConclusionsAmong subjects with moderate to severe COPD and normal LVEF, GLS independently predicted all-cause mortality. Exercise tolerance correlated with standard lung function parameters only in univariate models; in subsequent models including echocardiographic parameters, longer 6MWD correlated independently with milder TR, better DLCO SB, younger age and lower BMI. We extended the evidence on COPD affecting cardiac chamber volumes, LV preload, heart rate, as well as systolic and diastolic function. Our results highlight lung-heart interaction and the necessity of cardiac evaluation in COPD.

Right ventricular wall hypertrophy predicts functional capacity in pulmonary hypertension. A cardiac magnetic resonance study

Purpose: Right ventricular (RV) dilatation and wall hypertrophy is a compensatory mechanism to pressure and volume overload occurring in patients with pulmonary arterial hypertension (PAH). The aim of our study is to investigate the relationship between RV dimensions and wall thickness as accessed with cardiac magnetic resonance (CMR) and distance walked in 6-minute walking test (6MWD) in adult patients with PAH. Methods: All patients underwent 6 minute walking test (6MWT) and CMR on the same day. RV end diastolic (RVEDa) and end systolic area (RVESa) was obtained in short axis at the level of the papillary muscles at end diastole and end systole respectively and RV anterior wall thickness (RVWT) was measured at the same level at end diastole. Results: Our study included 14 patients with PAH (12 women, mean age 46.64±13.4 years), that walked 485.1±108.0 m in 6MWT. After controlling for confounding parameters as age, sex and body surface index, a negative correlation between distance walked in 6 minutes and RVWT (r=-0.671, p<0.001), RVESa (r=-0.660, p<0.01) and RVEDa (r=-0.704, p<0.005) was observed. Multivariate regression analysis showed that only RVWT is an independent predictor of 6MWD (B=-0.267, p<0.05) in the studied population (Table). View this table: Conclusions: The degree of RV hypertrophy may be used as a predictor of functional capacity of patients with PAH.

Impaired chronotropic response to 6-min walk test and reduced survival in interstitial lung disease

Reduced chronotropic response to maximal exercise has been associated with poor survival in people without respiratory disease. The contribution of chronotropic response to exercise limitation and survival in interstitial lung disease (ILD) is not well defined. This study investigated the relationships between chronotropic response during 6-min walk test, exercise capacity and survival in ILD. Eligible participants had ILD, were ambulant and free of heart failure and beta blocker therapy. Chronotropic response during the 6-min walk test was defined as peak heart rate (HR) minus resting HR. Survival was recorded at four years. Sixty-two participants (40 idiopathic pulmonary fibrosis) were included, with mean (SD) TLCO 50(18)% predicted and 6-min walk distance (6MWD) 377 (127) metres. A smaller chronotropic response was associated with reduced 6MWD (r=0.65, p<0.001). Independent predictors of 6MWD were chronotropic response, peak oxygen uptake on cardiopulmonary exercise test; right ventricular systolic pressure on echocardiogram; and age. This model explained 83% of the variance in 6MWD, with 24% of the variance attributable to chronotropic response. A chronotropic response during 6-min walk test of less than 20 beats per minute was an independent predictor of death at four years (odds ratio 10.71, 95% confidence interval 2.67-42.94) in a model that also included oxygen desaturation and forced vital capacity. Impaired chronotropic response to 6-min walk test is associated with reduced 6MWD and reduced survival in ILD, independent of physical fitness and pulmonary hypertension. Investigation of the mechanisms underlying attenuated HR response to exercise in ILD is warranted.

Quadriceps weakness contributes to exercise capacity in nonspecific interstitial pneumonia

It has been shown that peripheral muscle dysfunction is a critical factor in determining exercise intolerance in patients with several chronic lung diseases, including idiopathic pulmonary fibrosis. We hypothesized that exercise capacity would be, at least in part, determined by peripheral muscle dysfunction in patients with fibrotic nonspecific interstitial pneumonia (f-NSIP), another major subtype of fibrotic interstitial lung disease. The aim of the current study was to elucidate the relevance of peripheral muscle dysfunction and its contribution to exercise intolerance in f-NSIP. The six-minute walk test was evaluated in 30 consecutive patients with f-NSIP along with potential determinants of exercise capacity, including respiratory muscle force and peripheral muscle force. Among 30 patients, the median age was 61 years, and 21 were female. Sixteen patients showed significantly decreased quadriceps force (QF), and 17 had significant decreases in maximum expiratory pressure. Exercise capacity and muscle power were clearly related to sex. Adjusted for sex, QF showed a significant relation to exercise capacity measured by six-minute walk distance (6MWD), whereas pulmonary function parameters such as vital capacity showed marginal correlations. In stepwise multiple regression analysis, only QF was an independent predictor of 6MWD. Quadriceps weakness is often observed in patients with f-NSIP. It seems that QF significantly contributes to exercise capacity in this population.

Chronic Pain Is An Independent Predictor of Lower 6 Minute Walk Distance In Patients with Sickle Cell Disease: Results From Walk-PHaSST Study

AbstractAbstract 2658 Introduction:Six minute walk distance (6MWD), is a measure of exercise capacity commonly used as an endpoint in pulmonary hypertension (PH) clinical trials. Many patients with sickle cell disease (SCD) have acute pain crises or chronic pain syndromes that impair their quality of life. While patients with SCD who are undergoing screening for PH are generally screened in steady state, i.e., when they have not had a recent pain crisis, the impact of chronic pain on exercise capacity in this group of patients has not been previously evaluated. Methods:walk-PHaSST was a multi-center screening study designed to identify subjects with SCD at increased risk for symptomatic PH, defined by a tricuspid regurgitant velocity (TRV) ≥ 2.7 m/sec and 6MWD between 150–500 meters, for enrollment in a double-blind placebo controlled trial of sildenafil. The primary endpoint was the change in 6MWD after 16 weeks of treatment. We examined the relationship between subjects' self-reported acute and chronic pain and baseline 6MWD in the screened SCD patients in walk-PHaSST. Results:For 90% of subjects, the information about pain was reported by the patient or parent/family member. Documentation of pain management and utilization of services was verified from medical records in 10% of subjects. Ninety four percent of all subjects reported having a history of acute sickle cell pain crises; 6% reported never having had an acute pain crisis. For the subjects who reported a history of acute pain crises, the ‘typical’ acute pain rating on a scale of 0 to 10 was ≥ 7 (maximum 10) for 77% of this subset of subjects. A total of 342 (50%) subjects reported not having had any pain crises in the preceding week. Of 720 subjects screened medical history and 6 MWD was available in 673 patients. Of these 633 (94%) subjects did not report having had a pain crisis requiring an emergency department visit or hospitalization in the preceding week. A total of 39% of subjects reported chronic sickle cell related pain; no rating was reported for chronic pain. 88% of patients reported using medications for pain control while 15% reported using non-drug therapy including physical therapy in 3%, alternative therapy in 2%, acupuncture in 2% and hypnosis in < 1% of patients. The mean 6MWD for the screened population was 439 meters (median 438 m, range 123–713 m). A total of 171/673 (26%) subjects had a 6MWD >500 meters, which was above the screening cut-off for enrollment in the main interventional trial. By univariate analysis, subjects reporting chronic pain had a significant lower odds ratio for walking > 500 meters (OR 0.637, 95% C.I 0.44–0.99); a similar observation was seen with those subjects with a history of acute pain crises (OR 0.47, 95% C.I 0.24–0.91). Multivariable logistic regression analysis revealed a significant inverse relationship between chronic pain but not acute pain and 6MWD after adjusting for age, TRV, gender, hematocrit and smoking history (See Table 1). The mean 6MWD decreased by 27 meters with self reported chronic pain after adjusting for TRV, age, gender, hematocrit and 6MWD. Conclusions:TRV is a known predictor of 6MWD. However, these data suggest that patient self reported sickle cell related chronic pain is also an independent predictor of 6MWD. This relationship raises interesting questions about the potentially confounding effects of pain on exercise capacity as assessed by the 6MW test. Further study is warranted to investigate an association between chronic pain and exercise capacity in SCD as well as exploration of appropriate endpoints for future clinical trials in patients with SCD and suspected symptomatic PH.Table 1Odds Ratio estimates: Multivariable AnalysisParameterEstimateStandard ErrorWald 95% Confidence Limitsp-valueChronic Pain−27.28.0−42.9−11.60.0007TR Jet Velocity−30.69.9−49.9−11.10.0020Age−0.90.3−1.5−0.30.0022Sex−39.17.6−53.9−24.3<.0001 [Display omitted] Disclosures:Barst:Pfizer: Consultancy, Research Funding. Rosenzweig:Pfizer: Research Funding. Badesch:Pfizer: Honoraria, Research Funding. Hassell:Novartis: Research Funding.

Outcome measures of the 6 minute walk test: relationships with physiologic and computed tomography findings in patients with sarcoidosis

BackgroundWe assessed the relationship between physiologic parameters, computed tomography patterns, 6 minute walk distance (6MWD) and the distance-saturation product [DSP; defined as the product of the 6MWD and the lowest oxygen saturation during the 6 minute walk test (6MWT)]. In addition, we investigated factors affecting 6MWD in patients with pulmonary sarcoidosis.MethodsWe performed a retrospective study of patient demographics, treatment, pulmonary function, 6MWT, echocardiography and computed tomography results.ResultsFifty nine patients were included in this study. Their mean+standard deviation age was 47.5 years + 12.5 years, and 42 (71.2%) were female. Mean pulmonary function parameters for forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and total lung capacity (TLC) results, as percentages of predicted values, were 77.6 ± 22.2, 77.1 ± 22.8 and 78.7 ± 16.1, respectively. Comparison of the DSP with distance walked revealed a significant correlation with factors underlying reduced 6MWD, including gender, pulmonary function indices, partial pressure of oxygen (PaO2), and Borg dyspnea score. Other factors were significantly associated with DSP but not distance; these included lung fibrosis (p = 0.02), pulmonary hypertension (p = 0.01) and systemic therapy (p = 0.04). Backward elimination stepwise multiple regression analysis revealed that gender, and FEV1 were independent predictors of 6MWD, but FEV1 was more strongly related when DSP applied [DSP, R2 = 0.53, p = 0.02; distance, R2 = 0.45, p < 0.0001].ConclusionOur findings reveal that, compared to 6MWD alone, the DSP is correlated with a greater number of factors associated with reduced 6MWT performance. Therefore, the DSP may be a useful indicator of functional status in patients with sarcoidosis. Additional large-scale studies are warranted to validate our findings.

Six-Minute Walk Test and Health Status Assessment in Sarcoidosis

The 6-min walk test has proved useful in assessing impairment and prognosis in various lung diseases. A prospective study of 142 sarcoidosis patients seen during a 6-week period at one tertiary sarcoidosis clinic. All patients completed spirometry, 6-min walk testing, St. George Respiratory Questionnaire (SGRQ), fatigue assessment scale, and dyspnea score. Parameters assessed included the 6-min walk distance (6MWD) and the initial and lowest oxygen saturations during the test. One hundred three of 142 patients had extrapulmonary manifestations, 10 patients had left ventricular dysfunction, and 14 patients had documented pulmonary hypertension. Seventy-three patients (51%) completed a 6MWD < 400 m, and 32 patients (22%) walked < 300 m. The 14 patients with documented pulmonary hypertension had a shorter 6MWD (median, 280 m; range, 61 to 404) than those without documented pulmonary arterial hypertension (median, 411 m; range, 46 to 747; p < 0.0001). Several components of the pulmonary function and quality of life correlated with 6MWD. Using a stepwise multiple regression analysis, only SGRQ activity component (t = - 7.498, p < 0.0001), FVC (t = 4.415, p < 0.0001), and lowest oxygen saturation (t = 2.55, p < 0.02) were independent predictors of 6MWD. 6MWD was reduced in the majority of sarcoidosis patients. Several factors were associated with a reduced 6MWD, including FVC, oxygen saturation with exercise, and self-reported respiratory health. Both 6MWD and quality of life measures are useful in assessing the functional status of sarcoidosis patients.

Functional Predictors of Exertional Dyspnea, 6-min Walking Distance and HRCT Fibrosis Score in Idiopathic Pulmonary Fibrosis

Background: Exertional dyspnea and exercise incapacity are the most prominent and disabling symptoms and the main contributors to health-related quality of life in patients with idiopathic pulmonary fibrosis (IPF). Objectives: There are no comprehensive studies on pulmonary function tests (PFTs), dyspnea, exercise capacity and radiographic scores in IPF. We therefore sought to investigate the functional variables that can predict dyspnea, exercise capacity and disease extent in IPF. Methods: Thirty-four patients with IPF according to the ATS/ERS criteria underwent PFTs, Medical Research Council (MRC) dyspnea scoring, 6-min walking distance (6-MWD) and radiographic evaluation of fibrosis (HRCT score). Results: The 6-MWD (% pred.) was more impaired than PFTs. Residual volume (RV) showed the best correlation with the extent of fibrosis (r = –0.67, p = 0.0001) and, together with the alveolar-arterial gradient for O₂ [ΔP(A – a)O₂], was an independent predictor of disease extent (R² = 0.44). PFTs showed significant though weak correlations with MRC score and 6-MWD. According to the regression analysis, DL_CO and the HRCT fibrosis score were independent predictors of dyspnea, though they explained only 28% of the overall variance. FEV₁ and ΔP(A – a)O₂ were independent predictors of 6-MWD (R² = 0.31). Conclusions: PFTs and lung volumes in particular are closely related to the HRCT score, a measure of the extent of IPF. The correlation of dyspnea score and 6-MWD to PFTs is limited, due to the complexity of mechanisms leading to exercise limitation in IPF. Therefore dyspnea and exercise performance are largely independent indices and should be followed together with PFTs and HRCT score in order to better assess the status and progress of IPF patients.