Anosmia in Parkinson’s Disease in Pakistan: A Matched Case – Control Study

Objective:  To assess olfactory dysfunction in Parkinson's disease (PD) patients in Pakistan utilizing an autochthonous smell test. Setting:  Tertiary care center, single-center study. Materials and Methods:  Eighty-seven non-demented patients with PD, who fulfilled Queen Square Brain Bank Criteria were enrolled at the Movement Disorder Clinic, Lahore General Hospital (LGH), Lahore. Fifty-eight controls matched by gender, age, and place of residence were enrolled among patients and visitors attending other hospital clinics. Both groups underwent olfactory testing using the Pakistani Smell Identification test (PKSIT). The participants were required to identify the smell from a set of choices and were scored out of 10. Results:  Among patients in the study group, the mean duration of disease was 4.7 years (range 6 months to 19 years). The PD onset mean age was 52.15 ± 13.02 years among patients. The mean number of smell test items accurately recognized by the PD patients was 4.55 ± 2.4. A multiple linear regression demonstrated that age (P < 0.05) but not disease duration (P = 0.899) was a significant determinant of the smell test result in PD and control groups. The mean number of smell test items appropriately recognized by the controls was 7.33 ± 1.69. Logistic regression showed that the PKSIT had 73.2% sensitivity and 84.3% specificity to distinguish PD from control. Conclusion:  PKSIT being easily available, cheap, and more convenient to use in the Pakistani population, can be used in the evaluation of olfactory dysfunction in PD subjects.