1 research outputs found
Equating scores of the University of Pennsylvania smell identification test and sniffin' sticks test in patients with Parkinson's disease
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 âSniffinâ Sticksâ 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, Sniffinâ 16, and Brief-SIT (B-SIT); and Sniffinâ 12 and Sniffinâ 16 odour identification tests.
Methods
We used two incident cohorts of patients with PD who were tested with either the Sniffinâ 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 Sniffinâ 16 tests across the two groups. The IRT method shows very good characteristics between the true and converted Sniffinâ 16 (delta mean = 0.14, median = 0) based on UPSIT. The equipercentile conversion between the Sniffinâ 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 = â0.08, median = 0).
Conclusion
We have demonstrated that one can convert UPSIT to B-SIT or Sniffinâ 16, and Sniffinâ 12 to 16 scores in a valid way. This can facilitate direct comparison between tests aiding future collaborative analyses and evidence synthesis