title: Acute low back pain is marked by variability: An internet-based pilot study.
abstract: BACKGROUND
  Pain variability in acute LBP has received limited study. The objectives of this pilot study were to characterize fluctuations in pain during acute LBP, to determine whether self-reported 'flares' of pain represent discrete periods of increased pain intensity, and to examine whether the frequency of flares was associated with back-related disability outcomes.
  
  
  METHODS
  We conducted a cohort study of acute LBP patients utilizing frequent serial assessments and Internet-based data collection. Adults with acute LBP (lasting ≤3 months) completed questionnaires at the time of seeking care, and at both 3-day and 1-week intervals, for 6 weeks. Back pain was measured using a numerical pain rating scale (NPRS), and disability was measured using the Oswestry Disability Index (ODI). A pain flare was defined as 'a period of increased pain lasting at least 2 hours, when your pain intensity is distinctly worse than it has been recently'. We used mixed-effects linear regression to model longitudinal changes in pain intensity, and multivariate linear regression to model associations between flare frequency and disability outcomes.
  
  
  RESULTS
  42 of 47 participants (89%) reported pain flares, and the average number of discrete flare periods per patient was 3.5 over 6 weeks of follow-up. More than half of flares were less than 4 hours in duration, and about 75% of flares were less than one day in duration. A model with a quadratic trend for time best characterized improvements in pain. Pain decreased rapidly during the first 14 days after seeking care, and leveled off after about 28 days. Patients who reported a pain flare experienced an almost 3-point greater current NPRS than those not reporting a flare (mean difference [SD] 2.70 [0.11]; p < 0.0001). Higher flare frequency was independently associated with a higher final ODI score (ß [SE} 0.28 (0.08); p = 0.002).
  
  
  CONCLUSIONS
  Acute LBP is characterized by variability. Patients with acute LBP report multiple distinct flares of pain, which correspond to discrete increases in pain intensity. A higher flare frequency is associated with worse disability outcomes.
authors.affiliation: Division of PM&R, VA Boston Healthcare System, Boston, USA. pradeep.suri@va.gov
authors.forename: Pradeep
authors.initials: P
authors.lastname: Suri
authors.forename: James
authors.initials: J
authors.lastname: Rainville
authors.forename: Garrett M
authors.initials: GM
authors.lastname: Fitzmaurice
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.forename: Robert N
authors.initials: RN
authors.lastname: Jamison
authors.forename: Julia
authors.initials: J
authors.lastname: Martha
authors.forename: Carol
authors.initials: C
authors.lastname: Hartigan
authors.forename: Janet
authors.initials: J
authors.lastname: Limke
authors.forename: Cristin
authors.initials: C
authors.lastname: Jouve
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
mesh_terms: D059787:Acute Pain / Q000473:pathology* / Q000503:physiopathology; D015331:Cohort Studies; D003625:Data Collection / Q000379:methods*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D020407:Internet; D017116:Low Back Pain / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010865:Pilot Projects; D011795:Surveys and Questionnaires