Original article
Inappropriate use of bivariable analysis to screen risk factors for use in multivariable analysis,☆☆

https://doi.org/10.1016/0895-4356(96)00025-XGet rights and content

Abstract

The use of bivariable selection (BVS) for selecting variables to be used in multivariable analysis is inappropriate despite its common usage in medical sciences. In BVS, if the statistical p value of a risk factor in bivariable analysis is greater than an arbitrary value (often p = 0.05), then this factor will not be allowed to compete for inclusion in multivariable analysis. This type of variable selection is inappropriate because the BVS method wrongly rejects potentially important variables when the relationship between an outcome and a risk factor is confounded by any confounder and when this confounder is not properly controlled. This article uses both hypothetical and actual data to show how a nonsignificant risk factor in bivariable analysis may actually be a significant risk factor in multivariable analysis if confounding is properly controlled. Furthermore, problems resulting from the automated forward and stepwise modeling with or without the presence of confounding are also addressed. To avoid these improper procedures and deficiencies, alternatives in performing multivariable analysis, including advantages and disadvantages of the BVS method and automated stepwise modeling, are reviewed and discussed.

References (80)

  • J.J. Curtis et al.

    Impact of unstable angina on operative mortality with coronary revascularization at varying time intervals after myocardial infarction

    J Thorac Cardiovasc Surg

    (1991)
  • J. Jen et al.

    Allelic loss of chromosome 18q and prognosis in colorectal cancer

    N Engl J Med

    (1994)
  • H.B. Muss et al.

    c-erbB-2 expression and response to adjuvant therapy in women with node-positive early breast cancer

    N Engl J Med

    (1994)
  • P.M. Small et al.

    The epidemiology of tuberculosis in San Francisco-a population-based study using conventional and molecular methods

    N Engl J Med

    (1994)
  • M.A. Fiatarone et al.

    Exercise training and nutritional supplementation for physical frailty in very elderly people

    N Engl J Med

    (1994)
  • D.J. Cook et al.

    Risk factors for gastrointestinal bleeding in critically ill patients

    N Engl J Med

    (1994)
  • C.S. Cleeland et al.

    Pain and its treatment in outpatients with metastatic cancer

    N Engl J Med

    (1994)
  • A.G. Aprikian et al.

    Prostate adenocarcinoma in men younger than 50 years

    Cancer

    (1994)
  • B.A. Murphy et al.

    Serum tumor marker decline is an early predictor of treatment outcome in germ cell tumor patients treated with cisplatin and ifosfamide salvage chemotherapy

    Cancer

    (1994)
  • R.C. Newland et al.

    Pathologic determinants of survival associated with colorectal cancer with lymph node metastases

    Cancer

    (1994)
  • L.S. Yost et al.

    Determinants of subsequent home health care nursing service use by hospitalized patients with cancer

    Cancer

    (1993)
  • M.L. Christensen et al.

    Parenteral nutrition associated with increased infection rate in children with cancer

    Cancer

    (1993)
  • E. Abrutyn et al.

    Does asymptomatic bacteriuria predict mortality and does antimicrobial treatment reduce mortality in elderly ambulatory women?

    Ann Intern Med

    (1994)
  • D.B. Fishbein et al.

    Human ehrlichiosis in the United States, 1985 to 1990

    Ann Intern Med

    (1994)
  • L.J. Shaw et al.

    Gender difference in the noninvasive evaluation and management of patients with suspected coronary disease

    Ann Intern Med

    (1994)
  • A. Lynch et al.

    Antiphospholipid antibodies in predicting adverse pregnancy outcome

    Ann Intern Med

    (1994)
  • N.A. Rigotti et al.

    Predictors of smoking cessation after coronary artery bypass graft surgery

    Ann Intern Med

    (1994)
  • H.N. Hodis et al.

    Triglyceride- and cholesterol-rich lipoproteins have a differential effect on mild/moderate and severe lesion progression as assessed by quantitative coronary angiography in a controlled trial of lovastatin

    Circulation

    (1994)
  • T.R. Kimball et al.

    Cardiovascular status in young patients with insulin-dependent diabetes mellitus

    Circulation

    (1994)
  • M. Enriquez-Sarano et al.

    Echocardiographic prediction of survival after surgical correction of organic mitral regurgitation

    Circulation

    (1994)
  • A. Volpi et al.

    Determinants of 6-month mortality in survivors of myocardial infarction after thrombolysis-results of the GISSI-2 data base

    Circulation

    (1993)
  • M.A.A. Elayda et al.

    Aortic valve replacement in patients 80 years and older

    Circulation

    (1993)
  • G.E. Sarris et al.

    Randomized, prospective assessment of bioprosthetic valve durability-Hancock versus Carpentier-Edwards valves

    Circulation

    (1993)
  • R.L. Quigley et al.

    Prognosis and management of anterolateral myocardial infarction in patients with severe left main disease and cardiogenic shock-the left main shock syndrome

    Circulation

    (1993)
  • J.B. Wallis et al.

    Prognostic value of left ventricular ejection fraction response to exercise during long-term follow-up after coronary artery bypass graft surgery

    Circulation

    (1993)
  • L.J. Addonizio et al.

    Decreasing incidence of coronary disease in pediatric cardiac transplant recipients using increased immunosuppression

    Circulation

    (1993)
  • T.K. Rosengart et al.

    Reoperative coronary artery bypass surgery-improved preservation of myocardial function with retrograde cardioplegia

    Circulation

    (1993)
  • K. Yano et al.

    Determinants of the prognosis after a first myocardial infarction in a migrant Japanese population the Honolulu Heart Program

    Circulation

    (1993)
  • J.J. Popma et al.

    Vascular complications after balloon and new device angioplasty

    Circulation

    (1993)
  • J.D. Talley et al.

    Failured elective percutaneous transluminal coronary angioplasty requiring coronary artery bypass surgery

    Circulation

    (1990)
  • Cited by (0)

    The results, analyses, and opinions reported herein are those of the authors and in no way reflect on the opinions or judgments of the hospital, the B.C. McCabe Foundation, or The Los Angeles Thoracic and Cardiovascular Foundation.

    ☆☆

    This project would not have reached this stage without critical review from one of the anonymous referees.

    1

    The first author (G. W.S.) is partially supported by the B.C. McCabe Foundation (Whittier, CA) and The Los Angeles Thoracic and Cardiovascular Foundation (Los Angeles, CA).

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