Table 2

Characteristics of the included observational studies

Study name and fundingStudy designParticipants, settingExposed groupControl groupOutcomesNotes
Boltri et al,10 2002,
funding by the Health Resources and Services Administration
Retrospective cohort
Charts from two time periods were reviewed for a diagnosis of hypertension
24 family practice residents and 8 clinical attending physicians at the outpatient clinic of a family practice residency programme in south-eastern USA507 hypertensive patients during ‘Period 2’: January and February 1998 after the policy prohibiting samples distribution was implemented in August 1997 422 hypertensive patients during ‘Period 1’: January and February 1997 before the policy prohibiting samples distribution was implemented Effect of policy on prescription of first-line hypertension drugs versus prescription of second-line drugs by all physicians (by JNC VI) Data collection of the outcome was based on the medical reports of all hypertensive patients during the two study periods 
Spurling and Mansfield,12 2007,
funding not reported
Prospective cohort13 out of the 14 (7 part-time general practitioners (GPs), 3 practice nurses, 3 regular reception staff, 1 practice manager) participated
Inala Health Centre general practice in Brisbane, Australia 
Policy of reduced access to pharmaceutical sales representatives including: reception staff not to make appointments for representatives or accept promotional material; representatives not allowed to access sample cupboards; GPs wishing to see representatives only allowed to do so outside consulting hours Before policy implementation Number of prescription per patient (behaviour)Amount of promotional material (no further details provided)
Number of samples in the drug cupboard and time booked for pharmaceutical sales representatives (actual implementation of the policy) 
Timeframe: 2004
The impact of the policy was evaluated at 3 months and 9 months after its adoption
Data collected through audit and staff survey 
Hartung et al,11 2010,
funding partly by an American Academy of Family Physicians Foundation Research Stimulation Grant
Segmented linear regression models using locally obtained pharmacy claims The Madras Medical Group, a family practice clinic employing 5 physicians and 1 physician assistantAfter the implementation of a policy restricting access of pharmaceutical sales representatives to the clinic was implemented Before the implementation of the policy, Oregon Medicaid pharmacy claims were used to control for secular prescribing changesPercentage of branded drug use (behaviour) Percentage of promoted drug use (behaviour) Average prescription costs (cost)Time frame: 1 April 2004 to 31 September 2007
The Medicare Part D programme was implemented in January 2006
  • JNC VI, Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.