1 INTRODUCTION
Olfaction is an important sense of organisms that can regulate emotions, affect cog-nition and behaviour1,2, and also remind us of dangers in the environment3. It can be imp-aired by chronic rhinosinusitis, head trauma, infections, ageing, long-term smoking, alco-holism, metabolic diseases, and autoimmune diseases4. Olfactory dysfunction can signifi-cantly affect patients’ quality of life5, and it is an early marker of neurodegenerative dise-ases such as Alzheimer’s disease and Parkinson’s disease6,7.
The diagnosis and classification of olfactory dysfunction mainly depend on olfacto-ry psychophysical tests such as the Sniffin’ Sticks test8, the Connecticut Chemosensory Clinical Research Center test9, the University of Pennsylvania Smell Identification Test10, T&T test11, and so on. Among them, the Sniffin’ Sticks test has been the most widely us-ed. The test comprises an olfactory threshold test, olfactory discrimination test, and olfa-ctory identification test (SSOI test).
According to the research of Chrea et al.12, differences in culture, customs, and other factors in different countries and regions can lead to different people’s familiarity with th-e same smell. When subjects receive olfactory identification tests that are not suitable for their region, they may be unfamiliar with the odor itself or its distractors, which may aff-ect the results of olfactory tests. Therefore, many researchers designed olfactory test met-hods suitable for local people by changing odors and distractors. Among them, the modi-fied scheme for the Sniffin’ Sticks test is the most common. Dozens of countries and reg-ions, including Spain, Malaysia, Congo, and Turkey, have put forward the modified sche-me for the Sniffin’ Sticks test suitable for local people13-16.
In recent years, some researchers in China also have been committed to putting for-ward modified schemes of olfactory tests suitable for Chinese people. The Institute of Ps-ychology of the Chinese Academy of Sciences and the Beijing Anzhen Hospital, Affiliat-ed with Capital Medical University, have put forward the modified scheme of olfactory t-ests suitable for Chinese people, CSIT and COIT17,18. Although these two modified sche-mes used odors familiar to Chinese people to modify the olfactory identification test, the-y ignored two problems. First, both schemes only changed some odors but did not adjust the distractors of other options. Second, researchers mostly choose pleasant or neutral od-ors instead of unpleasant odors in most olfactory test modification schemes, including th-ese two modification schemes. The warning function is an important olfactory function, and most of the odors with warning functions are unpleasant odors, such as burnt smell in case of fire, special smells in case of natural gas leakage, etc.
To detect the olfactory function of subjects more comprehensively, it is necessary to introduce some unpleasant odors with warning function into olfactory tests. In this study, we modified the distractors in an olfactory identification test appropriately, and some un-pleasant odors with warning functions were introduced to modify the olfactory identifica-tion test. We aimed to design the Chinese Modified Olfactory Identification (CMOI) test based on the SSOI test and to present participants’ sensitivity to unpleasant odors.
2MATERIALS AND METHODS
For the development of this report, the STROBE guide for observational studies has been followed.