Table A5:

Methodological Quality of Included Economic Study (Ravikumar et al 2017⁵⁴

Question	Possible responses
Does the model structure adequately reflect the nature of the health condition under evaluation?	No. It did not include long-term clinical outcomes such as tremor recurrence.
Is the time horizon sufficiently long to reflect all important differences in costs and outcomes? (e.g., if the rate of mortality differs between interventions, does the model take a lifetime horizon?)	No. The time horizon used is unclear; it appears to be short-term.
Are all important and relevant health outcomes included?	Partly. Improvement in functional disability was associated with a different treatment, which was not reported.
Are the estimates of relative treatment effects obtained from the best available sources?	Partly. Nearly all included reports are uncontrolled observational studies.
Do the estimates of relative treatment effect match the estimates contained in the clinical report?	Not applicable. We were unable to check since the estimates were not reported clearly.
Are all important and relevant (direct) costs included in the analysis?	No. The publication did not include long-term costs such as treatment for tremor recurrence and deep brain stimulation device battery replacement.
Are the estimates of resource use obtained from the best available sources?	Yes.
Are the unit costs of resources obtained from the best available resources?	Yes.
Is an appropriate incremental analysis presented, or can it be calculated from the reported data?	Yes.
Are all important and uncertain parameters subjected to appropriate sensitivity analysis?	Unclear. The sensitivity analysis results were not fully presented.
Is there a potential conflict of interest?	Unclear.
Overall assessment	Minor limitations