Table 3: Criteria for the methodology quality assessment of prevalence studies. (Adapted and expanded from Prins et al.)

From: Alcohol consumption and erectile dysfunction: meta-analysis of population-based studies

Internal validity:
a) Was there a clearly focused objective?
Data collection
b) Were the data prospectively collected?
Measurement instrument
c) Was the measurement instrument validated?
d) Was the period covered by the measurement instrument specified?
Definition of variables
e) Was the definition of the outcome variable stated?
Reported prevalences
f) Was age-specific prevalence reported?
g) Were severity-related prevalences reported?
Causal analysis
h) Were possible statistical correlates of outcome variable reported?
i) Were alternative explanations considered?
External validity
Study population
j) Was there randomization involved in the selection of study subjects?
k) Did the recruitment of study subjects make them representative of the target population or patient population they claim to study?
Eligibility criteria
l) Was the age range specified?
m) Were inclusion and exclusion criteria specified?
Response rate
n) Was the response rateb at least 70%?
o) Were information given about the non-responders that allow inference to be made on the representativeness of the study population?
Description of study period
p) Was the study period specified?
Description of study population
q) Were demographic characterisitics of the study population given?a
r) Were implications of the results considered? (policy makers, clinicians, community)
Statistical adjustments for odds ratio
1) Was the odds ratio adjusted for age?
2) Was the odds ratio adjusted for education?
3) Was the odds ratio adjusted for income/occupation/socioeconomic status?
4) Was the odds ratio adjusted for depression?
5) Was the odds ratio adjusted for diabetes?
6) Was the odds ratio adjusted for hypertension?
7) Was the odds ratio adjusted for heart diseases?
8) Was the odds ratio adjusted for smoking?
9) Was the odds ratio adjusted for alcohol?
  1. aTwo or more of: (i) age distribution, (ii) relevant comorbidity, (iii) lifestyle factors (for example, smoking), (iv) socioeconomic data (for example, income, educational level, marital status).
  2. bTreated as completion rate for quality appraisal.