title: Correlation between Forced Vital Capacity and Slow Vital Capacity for the assessment of respiratory involvement in Amyotrophic Lateral Sclerosis: a prospective study.
abstract: BACKGROUND
  Slow vital capacity (SVC) and forced vital capacity (FVC) are the most frequent used tests evaluating respiratory function in amyotrophic lateral sclerosis (ALS). No previous study has determined their interchangeability.
  
  
  OBJECTIVE
  To evaluate SVC-FVC correlation in ALS.
  
  
  METHODS
  Consecutive definite/probable ALS and primary lateral sclerosis (PLS) patients (2000-2014) in whom respiratory tests were performed at baseline/4-6months later were included. All were evaluated with revised ALS functional rating scale, the ALSFRS respiratory (R-subscore) and bulbar subscores, SVC, FVC, maximal inspiratory (MIP) and expiratory (MEP) pressures. SVC-FVC correlation was analysed by Pearson product-moment correlation test. Paired t-test compared baseline/follow-up values. Multilinear regression analysis modelled the relationship between tested variables.
  
  
  RESULTS
  We included 592 ALS (332 men, mean onset age 62.6 ± 11.8 years, mean disease duration 15.4 ± 15 months) and 19 PLS (11 men, median age 54 years, median disease duration 5.5 years) patients. SVC and FVC predicted values decreased 2.15%/month and 2.08%/month, respectively. FVC and SVC were strongly correlated. Both were strongly correlated with MIP and MEP and moderately correlated with R-subscore for the all population and spinal-onset patients, but weakly correlated for bulbar-onset patients.
  
  
  CONCLUSIONS
  FVC and SVC were strongly correlated and declined similarly. This correlation was preserved in bulbar-onset ALS and in spastic PLS patients.
authors.affiliation: a Instituto de Medicina Molecular and Institute of Physiology, Faculty of Medicine , University of Lisbon , Portugal and.
authors.forename: Susana
authors.initials: S
authors.lastname: Pinto
authors.affiliation: a Instituto de Medicina Molecular and Institute of Physiology, Faculty of Medicine , University of Lisbon , Portugal and.|b Department of Neurosciences and Mental Health , Hospital de Santa Maria-Centro Hospitalar Lisboa Norte , Lisbon , Portugal.
authors.forename: Mamede
authors.initials: M
authors.lastname: de Carvalho
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012119:Respiration; D012120:Respiration Disorders / Q000175:diagnosis / Q000209:etiology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D013223:Statistics as Topic; D014797:Vital Capacity / Q000502:physiology*
keywords: Amyotrophic lateral sclerosis; forced vital capacity; functional rating scale; maximal respiratory pressures; slow vital capacity