Table 4.

Cross-sectional observational studies of relationship of Helicobacter-status to other outcomes in idiopathic parkinsonism.

Study	Ascertainment of Helicobacter-Positivity	Number Participants (Levodopa-Status)	Primary Relevant Outcome Measure	Findings
Dobbs et al. (2005) [58]	Serum immunoblot antibody profile	124 with IP and 194 without IP (81% on levodopa, evenly spaced to minimise fluctuations)	Body mass index	Odds of being underweight tripled in presence of anti-VacA † antibodies, irrespective of IP-status.
Suwarnalata et al. (2016) [59]	Serology (ELISA), anti-CagA, †† anti-H. pylori whole cell	60 with IP, of which 30 seropositive (unspecified number on levodopa)	Autoantibody screen	13 autoantibodies “against proteins essential for normal neurological functions” discriminated Helicobacter-positive from -negative.
Fasano et al. (2013) [60]	UBT	33 with IP of which 11 UBT-positive and 18 hydrogen breath test positive for SIBO # (all with levodopa-induced motor fluctuations)	Levodopa-induced motor complications	Unpredictable fluctuations were significantly more with SIBO plus Helicobacter-positivity, and tended to be more with SIBO alone, than in absence of both.
Rahne et al. (2013) [61]	UBT	40 with IP of which 20 UBT-positive (all taking levodopa)	Levodopa-induced motor complications	Helicobacter-positives had worse UPDRS-IV.

^† anti-vacuolating toxin. ^†† anti-cytotoxin-associated gene product. ^# SIBO = small intestinal bacterial overgrowth.