Cardiology · Medical Literature
Prognostic value of baseline and longitudinal changes in exercise capacity and quality of life in the HF-Wii Swedish population.
Abstract
This study aimed to explore whether baseline values and 12-month change in the 6-Minute Walk Distance (6MWD) and the physical scale of the Minnesota Living with Heart Failure Questionnaire (MLHFQ) were associated with long-term mortality in patients with heart failure (HF). A total of 333 patients with HF, enrolled in the HF-Wii trial (NCT01785121) in Sweden, were included. Data on long-term mortality were gathered 3 years after study completion of the last patient included. Study participants were stratified into three groups based on baseline results of the 6MWD: group 1: ≤383 m, group 2: 384-450 m and group 3: ≥451 m. Similarly, tertiles were formed according to baseline MLHFQ physical domain scores: group 1: 0-5 points, group 2: 6-12 points and group 3: 13-40 points. During a median (25th-75th percentiles) follow-up of 1900 (1566, 2271) days, 48 patients died (14.4%). Patients in group 1 of 6MWD displayed a more severe clinical status in comparison to patients in groups 2 and 3. Kaplan-Meier survival analysis showed a statistically significant between-group difference in survival, observed per tertile groups of the baseline 6MWD. However, no significant difference in survival was found in relation to changes in 6MWD over time. Likewise, there were not statistically significant between-group differences in survival per tertile groups of the baseline score on the physical domain of MLHFQ nor with respect to change over time of the same score. Baseline 6MWD demonstrated significant prognostic value for long-term mortality in patients with HF whereas the physical score of MLHFQ, as well as their 12-month changes did not reach statistical significance. NCT01785121.
Clinical relevance
Among patients with heart failure enrolled in the Swedish arm of the HF-Wii trial, are baseline 6-Minute Walk Distance (6MWD) and the physical domain score of the Minnesota Living with Heart Failure Questionnaire (MLHFQ), as well as their 12-month changes, independently associated with long-term all-cause mortality? __SNAPSHOT__ {"studyDesign":"Secondary analysis (post-hoc observational prognostic study) of a prospective randomized controlled trial cohort (HF-Wii; NCT01785121) with extended long-term mortality follow-up","setting":"Multicentre outpatient heart failure clinics, cardiology departments, and rehabilitation units in Sweden (Swedish sub-cohort of the international HF-Wii trial)","sampleSize":"n=333 (HF-Wii Swedish cohort; intervention/control allocation not stratified in this analysis)","population":"Adults with symptomatic heart failure (NYHA class I–IV, irrespective of ejection fraction) who were enrolled in the Swedish arm of the HF-Wii RCT, able to perform the 6-Minute Walk Test, and able to complete the MLHFQ; patients with severe visual, hearing, cognitive, or motor impairment were excluded from the parent trial","intervention":"Baseline and 12-month 6MWD (tertile groups: ≤383 m, 384–450 m, ≥451 m) and MLHFQ physical domain score (tertile groups: 0–5, 6–12, 13–40 points) as prognostic exposures; original trial randomized patients to exergaming (Nintendo Wii) vs. motivational support only","comparator":"Tertile-based subgroup comparisons within baseline 6MWD and MLHFQ physical domain scores; not applicable for the primary prognostic comparison","primaryOutcome":"Long-term all-cause mortality, assessed approximately 3 years after study completion of the last enrolled patient","followUp":"Median 1900 days (IQR: 1566–2271 days; approximately 5.2 years) [calculated: ~4.3–6.2 years IQR]","fundingSource":"Not reported in the abstract; parent HF-Wii trial was funded by non-industry sources including Swedish research councils (based on published trial design paper); confirm in full text"}
Key findings
Among 333 Swedish HF patients followed for a median of 1900 days (IQR 1566–2271 days), 48 patients died (all-cause mortality rate: 14.4% [calculated]). Patients were stratified into tertiles by baseline 6MWD (Group 1: ≤383 m; Group 2: 384–450 m; Group 3: ≥451 m) and by baseline MLHFQ physical domain score (Group 1: 0–5 points [least impaired]; Group 2: 6–12 points; Group 3: 13–40 points [most impaired]). Patients in the lowest 6MWD tertile (Group 1) exhibited more severe clinical status compared with Groups 2 and 3. Kaplan-Meier survival analysis demonstrated a statistically significant between-group difference in survival stratified by 6MWD tertile. Specific hazard ratios, confidence intervals, p-values for the log-rank test, and results for the MLHFQ physical domain tertile survival analysis are not reported in the abstract. The direction and magnitude of any association between 12-month change in 6MWD or MLHFQ and mortality, and results of any multivariable Cox regression adjusting for confounders, are not reported in the abstract. NNT and NNH cannot be calculated from the available data. No adverse event data are applicable to this prognostic analysis.
Practice implications
This study establishes an association between lower baseline exercise capacity (6MWD ≤383 m) and worse long-term survival in a Swedish HF cohort, consistent with existing literature demonstrating the prognostic value of the 6-Minute Walk Test in heart failure. Whether baseline MLHFQ physical domain scores and 12-month longitudinal changes in either measure independently predict mortality — after adjustment for age, ejection fraction, NYHA class, natriuretic peptides, and other established prognostic variables — cannot be determined from the abstract alone. The population is geographically restricted (Sweden), was drawn from a trial that excluded patients with significant sensory, cognitive, or motor impairment, and is likely to skew toward higher functional status than typical real-world HF populations, limiting generalizability to more severely ill or frail patients. The clinical importance of any between-tertile survival difference — beyond what is already captured by established prognostic tools — is not established from the abstract. Clinicians should note that this is a secondary analysis of a trial not powered for mortality, and the overall event count (n=48 deaths) is modest, which constrains the robustness of any multivariable prognostic model. Review of the full publication is essential before applying specific cut-points or findings to clinical practice. This summary is based on abstract-only data. __LIMITATIONS__ Abstract-only data available: specific effect sizes, adjusted hazard ratios, confidence intervals, and p-values for key comparisons are not reported and cannot be verified,Secondary post-hoc prognostic analysis of an RCT not powered for mortality; small total event count (n=48 deaths) limits statistical precision and the number of covariates that can be reliably adjusted in multivariable models,Single-country (Swedish) cohort limits generalizability to other healthcare systems, ethnicities, and HF management paradigms,Parent trial excluded patients with significant visual, hearing, cognitive, or motor impairment, potentially selecting a higher-functioning HF population than seen in routine care,Randomization arm (exergaming vs. motivational support) was not reported as a covariate in this analysis; differential intervention exposure may confound associations,Tertile cut-points for 6MWD and MLHFQ were empirically derived from this cohort and have not been externally validated as prognostic thresholds,The prognostic value of 12-month longitudinal change in 6MWD and MLHFQ over and above baseline values — a key stated aim — cannot be evaluated from the abstract,Potential for residual confounding by unmeasured variables (e.g., natriuretic peptide levels, ejection fraction subtype, comorbidity burden, pharmacotherapy),Survivorship bias: patients who completed 12-month assessments may differ systematically from those who died or were lost to follow-up earlier,Funding source not confirmed in abstract; potential conflicts of interest not assessable __BOTTOM_LINE_CATEGORY__ confirmatory __BOTTOM_LINE__ In a Swedish HF cohort followed for a median of approximately 5.2 years, lower baseline 6-Minute Walk Distance was associated with significantly worse survival on Kaplan-Meier analysis, consistent with established evidence. However, with only 48 deaths and abstract-only data available, the independent prognostic contribution of 12-month changes in 6MWD and MLHFQ physical domain score — beyond known confounders — cannot be confirmed, and full-text review is required before any clinical application of specific thresholds. These findings are directionally consistent with existing evidence and do not, in isolation, warrant a change in current practice.