Table 3.

Characteristics of the Excluded Studies.

Study (year)	Location	Design	Study population	Age	N	Confounders assessed	Diagnosis of PD	Diagnosis of ED	Reason for exclusion
Eltas (2013)	Turkey	Randomized controlled clinical trial P	Moderate or severe ED and periodontitis 30 to 40 years ≥20 teeth + male Exclusion-systemic diseases ( DM, HT, Heart disease) + Periodontal therapy last 12 months + systemic antibiotic last 6 months	ED + NSPT: 38.1 ± 6.1 ED: 36.6 ± 6.9	120 ED + NSPT = 60, ED = 60	CVD; DM HBP Periodontal therapy Smoking Systemic antibiotics	Oral examination AAP criteria (PI, BOP, PD, CAL) PL ≥ 4 mm AL ≥ 3 mm	IIEF ≥ 25	Selection bias, no control group
Matsumoto (2013)	Japan	Cross-sectional study R	88 male patients, Aged 20–85 Adjustment made for age alone	50.9 ± 16.6	88	None	CPD self-check sheet	IIEF ≥ 25	Confusing scoring system of periodontitis (self-check sheet for diagnosis of chronic periodontitis)
Uppal (2014)	India	Cross-sectional study	53 males, aged 25–40 ≥ 20 permanent teeth		53	Systemic diseases, Alcohol Smoking		SHIM questionnaire scores ≤ 21	Selection bias (included subjects were diagnosed with ED)/ No control group
Lee (2017)	Korea	Cohort study	Males ≥ 20 years		2,68,296	Age, income insurance residence area DM cerebral infraction myocardial infarction smoking angina pectoris health status	ICD-10codeK05.3		Periodontal flap surgery
Sharma (2011)	India	Cross-sectional	Males, 25–40 years ≥ 20 permanent teeth		103		Periodontal examination and radiographs	SHIM questionnaire scores ≤ 21	Selection bias, no control group