Equating scores of the University of Pennsylvania Smell Identification Test and Sniffin' Sticks test in patients with Parkinson's disease

Michael Lawton (Corresponding Author), Michele T. M. Hu, Fahd Baig, Claudio Ruffmann, Eilidh Barron, Diane M. A. Swallow, Naveed Malek, Katherine A. Grosset, Nin Bajaj, Roger A. Barker, Nigel Williams, David J. Burn, Thomas Foltynie, Huw R. Morris, Nicholas W. Wood, Margaret T. May, Donald G. Grosset, Yoav Ben-Shlomo

Research output: Contribution to journalArticle

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Abstract

BACKGROUND: Impaired olfaction is an important feature in Parkinson's disease (PD) and other neurological diseases. A variety of smell identification tests exist such as "Sniffin' Sticks" and the University of Pennsylvania Smell Identification Test (UPSIT). An important part of research is being able to replicate findings or combining studies in a meta-analysis. This is difficult if olfaction has been measured using different metrics. We present conversion methods between the: UPSIT, Sniffin' 16, and Brief-SIT (B-SIT); and Sniffin' 12 and Sniffin' 16 odour identification tests.

METHODS: We used two incident cohorts of patients with PD who were tested with either the Sniffin' 16 (n = 1131) or UPSIT (n = 980) and a validation dataset of 128 individuals who took both tests. We used the equipercentile and Item Response Theory (IRT) methods to equate the olfaction scales.

RESULTS: The equipercentile conversion suggested some bias between UPSIT and Sniffin' 16 tests across the two groups. The IRT method shows very good characteristics between the true and converted Sniffin' 16 (delta mean = 0.14, median = 0) based on UPSIT. The equipercentile conversion between the Sniffin' 12 and 16 item worked well (delta mean = 0.01, median = 0). The UPSIT to B-SIT conversion showed evidence of bias but amongst PD cases worked well (mean delta = -0.08, median = 0).

CONCLUSION: We have demonstrated that one can convert UPSIT to B-SIT or Sniffin' 16, and Sniffin' 12 to 16 scores in a valid way. This can facilitate direct comparison between tests aiding future collaborative analyses and evidence synthesis.

Original languageEnglish
Pages (from-to)96-101
Number of pages6
JournalParkinsonism & Related Disorders
Volume33
Early online date25 Sep 2016
DOIs
Publication statusPublished - Dec 2016

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Smell
Parkinson Disease
Meta-Analysis

Keywords

  • Olfaction
  • Sniffin’ Sticks
  • University of Pennsylvania Smell Identification Test
  • Equating
  • Item Response Theory

Cite this

Equating scores of the University of Pennsylvania Smell Identification Test and Sniffin' Sticks test in patients with Parkinson's disease. / Lawton, Michael (Corresponding Author); Hu, Michele T. M.; Baig, Fahd; Ruffmann, Claudio; Barron, Eilidh; Swallow, Diane M. A.; Malek, Naveed; Grosset, Katherine A.; Bajaj, Nin; Barker, Roger A.; Williams, Nigel; Burn, David J.; Foltynie, Thomas; Morris, Huw R.; Wood, Nicholas W.; May, Margaret T.; Grosset, Donald G.; Ben-Shlomo, Yoav.

In: Parkinsonism & Related Disorders, Vol. 33, 12.2016, p. 96-101.

Research output: Contribution to journalArticle

Lawton, M, Hu, MTM, Baig, F, Ruffmann, C, Barron, E, Swallow, DMA, Malek, N, Grosset, KA, Bajaj, N, Barker, RA, Williams, N, Burn, DJ, Foltynie, T, Morris, HR, Wood, NW, May, MT, Grosset, DG & Ben-Shlomo, Y 2016, 'Equating scores of the University of Pennsylvania Smell Identification Test and Sniffin' Sticks test in patients with Parkinson's disease' Parkinsonism & Related Disorders, vol. 33, pp. 96-101. https://doi.org/10.1016/j.parkreldis.2016.09.023
Lawton, Michael ; Hu, Michele T. M. ; Baig, Fahd ; Ruffmann, Claudio ; Barron, Eilidh ; Swallow, Diane M. A. ; Malek, Naveed ; Grosset, Katherine A. ; Bajaj, Nin ; Barker, Roger A. ; Williams, Nigel ; Burn, David J. ; Foltynie, Thomas ; Morris, Huw R. ; Wood, Nicholas W. ; May, Margaret T. ; Grosset, Donald G. ; Ben-Shlomo, Yoav. / Equating scores of the University of Pennsylvania Smell Identification Test and Sniffin' Sticks test in patients with Parkinson's disease. In: Parkinsonism & Related Disorders. 2016 ; Vol. 33. pp. 96-101.
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abstract = "BACKGROUND: Impaired olfaction is an important feature in Parkinson's disease (PD) and other neurological diseases. A variety of smell identification tests exist such as {"}Sniffin' Sticks{"} and the University of Pennsylvania Smell Identification Test (UPSIT). An important part of research is being able to replicate findings or combining studies in a meta-analysis. This is difficult if olfaction has been measured using different metrics. We present conversion methods between the: UPSIT, Sniffin' 16, and Brief-SIT (B-SIT); and Sniffin' 12 and Sniffin' 16 odour identification tests.METHODS: We used two incident cohorts of patients with PD who were tested with either the Sniffin' 16 (n = 1131) or UPSIT (n = 980) and a validation dataset of 128 individuals who took both tests. We used the equipercentile and Item Response Theory (IRT) methods to equate the olfaction scales.RESULTS: The equipercentile conversion suggested some bias between UPSIT and Sniffin' 16 tests across the two groups. The IRT method shows very good characteristics between the true and converted Sniffin' 16 (delta mean = 0.14, median = 0) based on UPSIT. The equipercentile conversion between the Sniffin' 12 and 16 item worked well (delta mean = 0.01, median = 0). The UPSIT to B-SIT conversion showed evidence of bias but amongst PD cases worked well (mean delta = -0.08, median = 0).CONCLUSION: We have demonstrated that one can convert UPSIT to B-SIT or Sniffin' 16, and Sniffin' 12 to 16 scores in a valid way. This can facilitate direct comparison between tests aiding future collaborative analyses and evidence synthesis.",
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note = "The Oxford Discovery study was funded by the Monument Trust Discovery Award from Parkinson's UK (J-0901 and J-1403) and supported by the National Institute for Health Research (NIHR) (HMRWAJO4) Oxford Biomedical Research Centre based at Oxford University Hospitals NHS Trust and University Of Oxford, and the NIHR Clinical Research Network: Thames Valley and South Midlands. The Tracking Parkinson's study was funded by Parkinson's UK (J-1101) and supported by the National Institute for Health Research (NIHR) DeNDRoN network, the NIHR Newcastle Biomedical Research Unit based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, and the NIHR funded Biomedical Research Centre in Cambridge. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.",
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TY - JOUR

T1 - Equating scores of the University of Pennsylvania Smell Identification Test and Sniffin' Sticks test in patients with Parkinson's disease

AU - Lawton, Michael

AU - Hu, Michele T. M.

AU - Baig, Fahd

AU - Ruffmann, Claudio

AU - Barron, Eilidh

AU - Swallow, Diane M. A.

AU - Malek, Naveed

AU - Grosset, Katherine A.

AU - Bajaj, Nin

AU - Barker, Roger A.

AU - Williams, Nigel

AU - Burn, David J.

AU - Foltynie, Thomas

AU - Morris, Huw R.

AU - Wood, Nicholas W.

AU - May, Margaret T.

AU - Grosset, Donald G.

AU - Ben-Shlomo, Yoav

N1 - The Oxford Discovery study was funded by the Monument Trust Discovery Award from Parkinson's UK (J-0901 and J-1403) and supported by the National Institute for Health Research (NIHR) (HMRWAJO4) Oxford Biomedical Research Centre based at Oxford University Hospitals NHS Trust and University Of Oxford, and the NIHR Clinical Research Network: Thames Valley and South Midlands. The Tracking Parkinson's study was funded by Parkinson's UK (J-1101) and supported by the National Institute for Health Research (NIHR) DeNDRoN network, the NIHR Newcastle Biomedical Research Unit based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, and the NIHR funded Biomedical Research Centre in Cambridge. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

PY - 2016/12

Y1 - 2016/12

N2 - BACKGROUND: Impaired olfaction is an important feature in Parkinson's disease (PD) and other neurological diseases. A variety of smell identification tests exist such as "Sniffin' Sticks" and the University of Pennsylvania Smell Identification Test (UPSIT). An important part of research is being able to replicate findings or combining studies in a meta-analysis. This is difficult if olfaction has been measured using different metrics. We present conversion methods between the: UPSIT, Sniffin' 16, and Brief-SIT (B-SIT); and Sniffin' 12 and Sniffin' 16 odour identification tests.METHODS: We used two incident cohorts of patients with PD who were tested with either the Sniffin' 16 (n = 1131) or UPSIT (n = 980) and a validation dataset of 128 individuals who took both tests. We used the equipercentile and Item Response Theory (IRT) methods to equate the olfaction scales.RESULTS: The equipercentile conversion suggested some bias between UPSIT and Sniffin' 16 tests across the two groups. The IRT method shows very good characteristics between the true and converted Sniffin' 16 (delta mean = 0.14, median = 0) based on UPSIT. The equipercentile conversion between the Sniffin' 12 and 16 item worked well (delta mean = 0.01, median = 0). The UPSIT to B-SIT conversion showed evidence of bias but amongst PD cases worked well (mean delta = -0.08, median = 0).CONCLUSION: We have demonstrated that one can convert UPSIT to B-SIT or Sniffin' 16, and Sniffin' 12 to 16 scores in a valid way. This can facilitate direct comparison between tests aiding future collaborative analyses and evidence synthesis.

AB - BACKGROUND: Impaired olfaction is an important feature in Parkinson's disease (PD) and other neurological diseases. A variety of smell identification tests exist such as "Sniffin' Sticks" and the University of Pennsylvania Smell Identification Test (UPSIT). An important part of research is being able to replicate findings or combining studies in a meta-analysis. This is difficult if olfaction has been measured using different metrics. We present conversion methods between the: UPSIT, Sniffin' 16, and Brief-SIT (B-SIT); and Sniffin' 12 and Sniffin' 16 odour identification tests.METHODS: We used two incident cohorts of patients with PD who were tested with either the Sniffin' 16 (n = 1131) or UPSIT (n = 980) and a validation dataset of 128 individuals who took both tests. We used the equipercentile and Item Response Theory (IRT) methods to equate the olfaction scales.RESULTS: The equipercentile conversion suggested some bias between UPSIT and Sniffin' 16 tests across the two groups. The IRT method shows very good characteristics between the true and converted Sniffin' 16 (delta mean = 0.14, median = 0) based on UPSIT. The equipercentile conversion between the Sniffin' 12 and 16 item worked well (delta mean = 0.01, median = 0). The UPSIT to B-SIT conversion showed evidence of bias but amongst PD cases worked well (mean delta = -0.08, median = 0).CONCLUSION: We have demonstrated that one can convert UPSIT to B-SIT or Sniffin' 16, and Sniffin' 12 to 16 scores in a valid way. This can facilitate direct comparison between tests aiding future collaborative analyses and evidence synthesis.

KW - Olfaction

KW - Sniffin’ Sticks

KW - University of Pennsylvania Smell Identification Test

KW - Equating

KW - Item Response Theory

U2 - 10.1016/j.parkreldis.2016.09.023

DO - 10.1016/j.parkreldis.2016.09.023

M3 - Article

VL - 33

SP - 96

EP - 101

JO - Parkinsonism & Related Disorders

JF - Parkinsonism & Related Disorders

SN - 1353-8020

ER -