Cristin-resultat-ID: 1031578
Sist endret: 28. oktober 2016 16:36
NVI-rapporteringsår: 2013
Resultat
Vitenskapelig artikkel
2013

Two to five repeated measurements per patient reduced the required sample size considerably in a randomized clinical trial for patients with inflammatory rheumatic diseases

Bidragsytere:
  • Geir Smedslund
  • Heidi Andersen Zangi
  • Petter Mowinckel og
  • Kåre Birger Hagen

Tidsskrift

BMC Research Notes
ISSN 1756-0500
e-ISSN 1756-0500
NVI-nivå 1

Om resultatet

Vitenskapelig artikkel
Publiseringsår: 2013
Volum: 6
Hefte: 37
Open Access

Beskrivelse Beskrivelse

Tittel

Two to five repeated measurements per patient reduced the required sample size considerably in a randomized clinical trial for patients with inflammatory rheumatic diseases

Sammendrag

Background: Patient reported outcomes are accepted as important outcome measures in rheumatology. The fluctuating symptoms in patients with rheumatic diseases have serious implications for sample size in clinical trials. We estimated the effects of measuring the outcome 1-5 times on the sample size required in a two-armed trial. Findings: In a randomized controlled trial that evaluated the effects of a mindfulness-based group intervention for patients with inflammatory arthritis (n=71), the outcome variables Numerical Rating Scales (NRS) (pain, fatigue, disease activity, self-care ability, and emotional wellbeing) and General Health Questionnaire (GHQ-20) were measured five times before and after the intervention. For each variable we calculated the necessary sample sizes for obtaining 80% power (α=.05) for one up to five measurements. Two, three, and four measures reduced the required sample sizes by 15%, 21%, and 24%, respectively. With three (and five) measures, the required sample size per group was reduced from 56 to 39 (32) for the GHQ-20, from 71 to 60 (55) for pain, 96 to 71 (73) for fatigue, 57 to 51 (48) for disease activity, 59 to 44 (45) for self-care, and 47 to 37 (33) for emotional wellbeing. Conclusions : Measuring the outcomes five times rather than once reduced the necessary sample size by an average of 27%. When planning a study, researchers should carefully compare the advantages and disadvantages of increasing sample size versus employing three to five repeated measurements in order to obtain the required statistical power.

Bidragsytere

Aktiv cristin-person

Geir Smedslund

  • Tilknyttet:
    Forfatter
    ved Nasjonal kompetansetjeneste for revmatologisk rehabilitering (NKRR) ved Diakonhjemmet sykehus
Aktiv cristin-person

Heidi Andersen Zangi

  • Tilknyttet:
    Forfatter
    ved Nasjonal kompetansetjeneste for revmatologisk rehabilitering (NKRR) ved Diakonhjemmet sykehus

Petter Mowinckel

Bidragsyterens navn vises på dette resultatet som Petter Mowinckel
  • Tilknyttet:
    Forfatter
    ved Nasjonal kompetansetjeneste for revmatologisk rehabilitering (NKRR) ved Diakonhjemmet sykehus
Aktiv cristin-person

Kåre Birger Hagen

  • Tilknyttet:
    Forfatter
    ved Nasjonal kompetansetjeneste for revmatologisk rehabilitering (NKRR) ved Diakonhjemmet sykehus
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