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Advanced Neurology LBD prevalence and incidence in India

2.3. Data analysis 3.5. Cognitive scales and biomarkers

When prevalence was not reported by individual studies, Only one study included the Mini-Mental State
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we calculated DLB prevalence as the percentage of DLB Examination (MMSE). Table 1 shows the details of the
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cases among the total number of dementia cases. When language of administration and each version’s validation
PDD prevalence was not reported using other methods, it status. The remaining study used the Kolkata Cognitive
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was calculated as the number of PD cases diagnosed with Screening Battery (KCSB), 27,28 which comprises verbal
dementia divided by the entire PD population during the fluency, calculation, visuospatial, and both immediate
screening period. and delayed recall tasks adapted from the Consortium
When confidence intervals were not identified, we to Establish a Registry for Alzheimer’s Disease
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used the Epitools (epitools.ausvet.com.au) online resource neuropsychological battery. Although the language in
and the Wilson calculation method to estimate these. which the KCSB was administered was not specified by
This method provides more accurate intervals for small the study, KCSB has been validated in both Bengali, the
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sample sizes, which we anticipated would be represented most commonly spoken language in Kolkata, and Hindi.
in the included studies. Unlike the symmetric normal Other scales included the Addenbrooke’s cognitive
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approximation interval, the Wilson score interval is examination-revised version, the scale for the outcome
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asymmetric, avoiding the issues of overshoot and zero- of PD-Cognition, and the Frontal Assessment Battery.
width interval that affect normal intervals. 17 One study used single photon emission computed
tomography and positron emission tomography imaging
3. Results in the subtype diagnosis, but specific biomarkers were
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not discussed.
3.1. Search results
Of the 1372 studies identified by our search, 399 were 3.6. Quality assessment
subjected to full-text reviews (Figure 1) and data were We conducted a quality assessment for each study to
extracted from 4. ensure the reliability of this systematic review. This helped
identify gaps in evidence, enhanced transparency and
3.2. Prevalence and incidence
reproducibility, and minimized the waste of valuable
All four studies discussed the prevalence of either DLB, resources. A quality assessment was essential to achieve
PDD, or LBD, and none reported the incidence of DLB, a rigorous and reliable systematic review. Hence, to
PDD, or LBD. Two studies described DLB 18,19 cohorts: one guarantee the dependability of this research, the JBI
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PDD cohort and one study reported on an LBD cohort quality assessment was used because it has checklists for
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but did not specify the number of subjects with PDD and different study designs, and it was performed using an
DLB (Table 1). The mean age of participants varied; some acritical appraisal tool. This appraisal aimed to thoroughly
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studies had an age range of 38 – 50 years, whereas others evaluate the methodological quality of a particular study.
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included participants >50 years. The average proportion of It also comprehensively assessed the entire research
females across the four studies was 37%. process, including the design, conduct, and analysis. In
addition, the appraisal aimed to determine the extent
3.3. Study design to which the study has considered the possibility of bias
Studies reporting DLB and LBD adopted a cross-sectional and implemented measures to address it appropriately.
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survey design, whereas the study investigating PDD The quality assessment checklist for each study type was
(Table 1) adopted a prospective cohort. 18-21 Table 1 shows filled out in a Microsoft Excel spreadsheet (Appendix 2).
the setting and recruitment for each study. The assessment quantitatively scored papers on a scale of
1 for “Yes” and 0 for “No.” Although assigning quantitative
3.4. Diagnostic criteria scores for “unclear” and “not applicable” is possible, this
Two studies investigated DLB populations. One study approach could lead to the arbitrary exclusion of papers.
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cited the third report of the 2005 international consortium Consequently, the inclusion of papers would be subjective
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criteria for defining DLB, whereas the other used rather than based on a quantitative scoring system.
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separate criteria, also published in 1996 for “diffuse Subsequently, HPK customized the data extraction tool
LBD”. The studies investigating PDD and LBD used to suit the specific requirements of the study (Appendix
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the Diagnostic and Statistical Manual of Mental Disorders 3) by modifing the existing JBI’s prevalence and incidence
3 edition–Revised (DSM-III-R) and Diagnostic extraction tool (Appendix 4). The studies’ information
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rd
and Statistical Manual of Mental Disorders 4 edition was extracted from the papers and compiled into a
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(DSM-IV), respectively. Microsoft Excel spreadsheet.
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Volume 3 Issue 4 (2024) 3 doi: 10.36922/an.4098