Table 1

Study characteristics*

ReferenceYearAuthorStudy designPopulationFollow-up (years)Exposure to outcome (years)Cohort sizePD casesControlDefinition of PDDefinition of constipationExposure assessment
161997GoneraCase–control63 general practices10NKNA6058Neurologist diagnosed, Queen Square Brain Bank CriteriaICPC definedGeneral practice record review
152001AbbottCohortHonolulu Heart Program24126790966694Hospital records/death certificates/neurologist diagnosed<1 BM per day (≤3 per week) compared with dailyStructured questionnaire
172009SavicaCase–controlRochester Epidemiology Project, Olmsted County, Minnesota38>20NA196196Medical record review (2/4 cardinal features excluding other causes). ValidatedDiagnosis of constipation or use of laxativesMedical record review
62011GaoCohortHealth Professionals Follow up Study6NK33 90115633 745Neurologist diagnosed or 2/3 of cardinal features excluding other causesBM every 3 days or less (<3 per week) compared with dailyStructured questionnaire
62011GaoCohortNurses’ Health Study24NK93 7673793 730Neurologist diagnosed or 2/3 of cardinal features excluding other causesBM every 3 days or less (<3 per week) compared with dailyStructured questionnaire
72014PlouvierCase–controlCMR database; University of Nijmegen2NK12 0008678GP or neurologist diagnosed—coded within CMR databaseDiagnosis in the CMR databaseCMR record review
82014LinCohortNational Health Insurance Database5.5NK551 3242336548 988Hospital discharge diagnosis or neurologist diagnosedDiagnosis in database and use of laxativesDatabase review
92014SchragCase–controlHealth Improvement Network UK Primary care database14>10NA816646 755Read code in database and ≥2 PD medicationsRead code in database or laxative prescriptionDatabase review
102014Pont-SunyerCase–control11 outpatient clinics>10>10NA109107Queen Square Brain Bank Criteria3 months of <3 BMs per week or strainingNMS questionnaire
  • *Abridged table; see supplementary table S1 for complete table.

  • BM, bowel movement; CMR, continuous morbidity registration; GP, general practitioner; ICPC, International classification of primary care; NA, not available; NMS, non motor symptom; PD, Parkinson's disease.