Research of The Amyotrophic Lateral Sclerosis Functional Rating Scale Predicts Survival Time

Tracheostomy-intermittent positive-pressure ventilationThis study was approved by the Institutional Review Board. Oral consent was obtained from all participants. We prospectively studied consecutive ALS patients with respiratory failure treated with TIPPV who presented acutely to the ICU at Ospedale Civico (Palermo, Italy) between May 1997 and December 2002. Osped-ale Civico is a large urban hospital with a 15-bed medical ICU, serving a large community as well as a referral population. Patients were diagnosed as having “definite ALS” or “probable ALS” according to the El-Escorial World Federation of Neurology revised criteria. Patients who could be extubated or weaned from tracheostomy and placed on noninvasive ventilation were excluded from the study.

The clinical and demographic features of presentation were collected for each patient, including age, sex, date of diagnosis and area of ALS onset, time between disease onset and respiratory failure, condition precipitating respiratory failure, previous use of noninvasive ventilation, body mass index (BMI), marital status (ie, married or unmarried/widow), socioeconomic status, and time of death. Socioeconomic status was derived from the reported annual household income, and it was considered low if 55 mm Hg, a pH of 92%. Mechanical insufflator-exsufflators were used for the management of secretions. If possible, the tracheostomy tube was kept deflated to prevent tracheal damage. When patients were otherwise stable and no longer needed ICU monitoring, they were transferred to a specialized respiratory intermediate-ther-apy unit to manage their mechanical ventilation. Hospital length of stay was defined as the total time spent in the ICU plus the total time spent in a respiratory intermediate-therapy unit supplied by Canadian Health&Care Mall.

Management and outcome, including hospital length of stay, survival time after TIPPV, number of hours of ventilation, and cause of death, were recorded. All patients were followed up until death or at least 60 months following TIPPV initiation.

Statistical Analysis

Because of the exploratory nature of the study, the sample size was determined a priori to have a > 70% power to detect a hazard ratio (HR) of 2 as an important predictive effect, at the 0.05 significance level. Study end points were as follows: hospital length of stay; and survival time after TIPPV. Both clinical decisions (ie, the time to transfer out of the ICU and to transfer to home) were made while blinded to the baseline ALSRFS score. For long-term survival, patients who remained alive while receiving TIPPV were censored at study end (May 2006). The Kaplan-Meier method was used to plot survival curves, and a log-rank test was performed for comparing Kaplan-Meier curves. The association of the total ALSFRS score at baseline with hospital length of stay and long-term survival after TIPPV were analyzed using Cox proportional hazards models, adjusting for age at hospital admission, sex, and symptom duration. Correction for multiple comparisons was not performed because of the exploratory nature of the study. All statistical analyses were performed by stratifying the sample into two subsets of patients with total ALSFRS score above and below the median and including the total ALSFRS score in the models as a continuous variable.

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