Objectives. We sought to analyze the disease-free intervals and calculate the freedom from atherosclerosis events in the Program on the Surgical Control of the Hyperlipidemias (POSCH). Background. The POSCH study was a randomized, secondary lipid/atherosclerosis intervention trial that provided strong evidence for reduction in atherosclerosis progression as demonstrated by clinical and arteriographic end points. The 417 control group patients received American Heart Association phase II diet instruction, and the 421 intervention group patients received identical dietary instruction and underwent a partial ileal bypass operation. Methods. Four outcome measures were determined: 1) overall mortality, 2) coronary heart disease mortality, 3) coronary heart disease mortality and confirmed nonfatal myocardial infarction, and 4) coronary/cardiac interventions. Results. An overall mortality rate of 10% occurred at 6.7 years in the control group and 9.4 years in the intervention group, for a gain in disease-free interval of 2.7 years in the intervention group (p = 0.032). A coronary heart disease mortality rate of 8% occurred at 7.2 years in the control group and 11 years in the intervention group, for a gain of 3.8 years (p = 0.046). Twenty percent of patients demonstrated the combined end point of coronary heart disease mortality and confirmed nonfatal myocardial infarction at 5.9 years in the control group and 11.4 years in the intervention group, for a gain of 5.5 years (p < 0.001). Twenty-five percent of patients underwent either coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty or heart transplantation at 5.4 years in the control group and 12.4 years in the intervention group, for a gain of 7 years (p < 0.001). Conclusions. The marked lipid modification achieved by partial ileal bypass in the POSCH trial led to demonstrable increases in the disease-free intervals for overall mortality, coronary heart disease mortality, coronary heart disease mortality and confirmed nonfatal myocardial infarction, and coronary intervention procedures. For the clinician and the patient, estimation of disease-free intervals may be more relevant than assessment of differences in incidence rates and risk ratios.
Bibliographical noteFunding Information:
Analyses of the relative disease-flee intervals in the control and intervention groups for clinical end points in atherosclerosis intervention trials, in particular, in lipid/atherosclerosis intervention trials, are absent from published reports. The major dietary, pharmacologic, surgical and life-style intervention trials, including the Program on the Surgical Control of the Hyperlipidemias (POSCH) study, have not provided data on disease-free intervals or differences in disease-free intervals between control a~d intervention groups, for overall mortality, coronary heart disease mortality, nonfatal myocardial infarc- Fromt he Departmento f Surgerya nd Schoolo f Public Health,U niversityo f Minnesota, Minneapolis,M innesota;a nd *Divisiono f CardiothoracieS urgery, New EnglandD eaconessH ospital and Harvard MedicalS chool,B oston,M as-sachusetts. This study was supported by Grants R01-HL1 5265 and R01-HL-49522 fromt he NationalH eart, Lung,a nd BloodI nstitute,N ationalI nstituteso f Health, Bethesda, Maryland. A list of the participating investigators and institutionsf or the POSCH Group appears in the Appendix. Manuscript received December 13, 1994; revised manuscript received, accepted April 4, 1995. Address for corresoondence:D r. HenryB uchwald,B ox 290 UMHC,U ni-versityo f Minnesota,4 20 DelawareS treet SE, Minneapolis,M innesota5 5455.