Ives 1994

Methods	Purpose: to compare offer of free influenza vaccination in capitated care groups to fee‐for‐service care groups and to no offer Design: RCT, participants randomised Duration of study: 1 May to 31 December 1989 Interval between intervention and when outcome was measured: April 1991 to March 1992 Power computation: not provided Statistics: Chi2; logistic regression controlling for age, gender, marital status, education, insurance and intervention group
Participants	Country: USA Setting: community‐dwelling Medicare beneficiaries 65 to 79 in rural Pennsylvania Eligible participants: (health status) 3884 enrolled in demonstration project, of whom 3606 (92.8%) completed follow‐up telephone interview; then limited study population to those interviewed between April 1991 and March 1992 = 1989 community‐dwelling Medicare beneficiaries 65 to 79. Exclusions: institutionalised, non‐ambulatory, life‐threatening dx cancer in previous 5 years Age: 65 Gender: not stated
Interventions	Intervention 1: patients participating in capitated payment group: after health risk appraisal interview randomly assigned to offer of no cost influenza immunisation Intervention 2: patients participating in fee‐for‐service group; after health risk appraisal interview randomly assigned to offer of no cost influenza immunisation; physicians only paid if they received and submitted payment voucher from participants Control: given their health risk appraisals but not offered immunisation This helpful e‐mail was received from Dr. Diane Ives: "Regarding the issues of bias, this was a community based demonstration project to see if Medicare beneficiaries would use prevention programs if offered at no cost. Everyone enrolled in Medicare Part B was potentially eligible and contacted to invite participation. Due to the nature of the programs, it was impossible to blind the providers or participants. However, subjects were randomly assigned to one of the 3 comparison groups (hospital based, physician based and control/no free services), with the exception that spouse pairs were assigned to the same group for feasibility of both using the services. The 2 references below detail the characteristics of people who came into the program based on various recruitment methods, and also describe those who did not participate.  We found people who participated had more disease history and risk factors, people who were contacted but refused to participate were the healthiest and possibly refused because they felt they did not have the risk factors targeted by the interventions, and those unable to be reached had highest levels of disease based on Medicare claims data and may have been too ill to participate Ives DG, Kuller LH, Schulz R, Traven ND, Lave JR.  Comparison of recruitment strategies and associated disease prevalence for health promotion in rural elderly.  Preventive Medicine 1992;21:582‐591 Ives DG, Traven ND, Kuller LH, Schulz R. Selection bias and nonresponse to health promotion in older adults.  Epidemiology 1994;5:456‐461."
Outcomes	Outcome measured: % vaccinated, measured by self report and by completed flu vouchers for payment to physician by Medicare Time points from the study that are considered in the review or measured or reported in the study: April 1991 to March 1992 % vaccinated by March 1992 (2.5 years after study began, 1.5 years after offer of influenza vaccine)
Notes	Funding: Health Care Financing Administration
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"... participants were randomly assigned" (no statement about method)
Allocation concealment (selection bias)	Unclear risk	No statement
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Measured by self report, but also by completed flu vouchers for payment to physician by Medicare
Incomplete outcome data (attrition bias) All outcomes	Low risk	All 1989 participants enrolled were analysed
Selective reporting (reporting bias)	Low risk	No selective reporting