Who can respond to treatment? Identifying patient characteristics related to heterogeneity of treatment effects.
BACKGROUND
Interest in comparative effectiveness research and the rising number of negative or "small effect" trials have stimulated research into differential response to treatment among subgroups of patients.


OBJECTIVE
To develop and test the Potential for Benefit Scale (PBS), a composite measure to identify subgroups of patients with differential potential for response to treatment, using diabetes as a model.


METHODS
Cross-sectional and longitudinal cohort study.


METHODS
Type 2 diabetes patients (n = 1361) were identified from 7 outpatient clinics serving a diverse population. Of these, 611 completed a 1-year follow-up.


METHODS
To represent patients' health status, we used the Total Illness Burden Index, the Physical Function Index of the SF-36, the Center for Epidemiologic Studies Depression Scale, and the Diabetes Burden Scale. To represent personality characteristics related to health, we used the Provider-Dependent Health Care Orientation scale. We assessed the contribution of these measures to a composite scale of patients' potential for treatment response in terms of self-reported medication adherence and glycemic control.


RESULTS
Principal components analysis confirmed associations among these measures. The internal consistency reliability of the PBS was adequate (Cronbach alpha = 0.65). Patients in the lowest versus highest quartile of the PBS reported poorer adherence (18% vs. 55%, P < 0.001) and poorer glycemic control at baseline (mean hemoglobin A1c values: 7.75 vs. 7.39, P < 0.001). Those in the highest quartile of the PBS also were more likely to reach target values for glycemic control (HbA1c <7%) at 1-year follow-up, (adjusted OR = 1.61, P < 0.05).


CONCLUSIONS
The PBS, a composite scale, may be helpful in identifying patients with differential potential for response to treatment.
Kaplan
Sherrie H
SH
Health Policy Research Institute, Department of Medicine, University of California, Irvine, CA 92697, USA. skaplan@uci.edu
Billimek
John
J
Sorkin
Dara H
DH
Ngo-Metzger
Quyen
Q
Greenfield
Sheldon
S
D000367:Age Factors; D000368:Aged; D001786:Blood Glucose; D002648:Child; D015897:Comorbidity; D057186:Comparative Effectiveness Research / Q000458:organization & administration*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000523:psychology* / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin; D006801:Humans; D055118:Medication Adherence; D008875:Middle Aged; D010551:Personality; D012720:Severity of Illness Index; D012737:Sex Factors; D012959:Socioeconomic Factors
D001786:Blood Glucose; D006442:Glycated Hemoglobin
Health Qual Life Outcomes. 2010 Jan 23;8:9
20096129
N Engl J Med. 2009 Nov 5;361(19):1897-9
19890133
Heart. 2007 Jul;93(7):783-4
17569802
Soc Sci Med. 2004 Oct;59(8):1629-46
15279921
Circulation. 2000 Aug 8;102(6):630-5
10931802
Arch Intern Med. 2000 Nov 27;160(21):3278-85
11088090
J Affect Disord. 2005 Nov;88(3):269-78
16165217
Psychosomatics. 1996 Sep-Oct;37(5):459-68
8824126
N Engl J Med. 2006 Apr 20;354(16):1706-17
16531616
J Am Geriatr Soc. 1996 Nov;44(11):1314-21
8909346
J Aging Health. 2005 Oct;17(5):634-60
16177454
JAMA. 2007 Sep 12;298(10):1209-12
17848656
JAMA. 2003 Sep 24;290(12):1624-32
14506122
J Gen Intern Med. 2003 Aug;18(8):609-16
12911642
Ann Intern Med. 2009 Aug 4;151(3):206-9
19567619
Med Care. 1995 Apr;33(4 Suppl):AS47-55
7723461
Ann Intern Med. 2008 Apr 15;148(8):578-86
18413619
J Clin Epidemiol. 2009 May;62(5):464-75
19348971
Urology. 1999 Sep;54(3):424-9
10475347
Diabetes Care. 1994 Jun;17 Suppl 1:32-9
8088221
BMJ. 1999 May 29;318(7196):1460-7
10346775
Ann Intern Med. 2009 Aug 4;151(3):203-5
19567618
Stroke. 2003 Feb;34(2):464-7
12574561
J Pers Soc Psychol. 1998 Mar;74(3):763-73
9523418
N Engl J Med. 2008 Jun 12;358(24):2545-59
18539917
Milbank Q. 2004;82(4):661-87
15595946
Can J Psychiatry. 2008 Jun;53(6):361-70
18616856
Ann Intern Med. 2009 Dec 15;151(12):854-60
20008761
Lancet. 2007 Sep 8;370(9590):851-8
17826170
Cancer. 2007 May 1;109(9):1777-83
17354226
Health Psychol. 2004 Mar;23(2):119-25
15008654
N Engl J Med. 2006 Feb 16;354(7):669-83
16481635
J Health Psychol. 2004 Sep;9(5):627-47
15310418
Health Aff (Millwood). 2005 Nov-Dec;24(6):1571-81
16284031
Arch Intern Med. 2000 Jul 24;160(14):2101-7
10904452
Am J Med. 2007 Apr;120(4 Suppl 1):S3-9
17403380
Am J Health Promot. 1996 Mar-Apr;10(4):282-98
10159709
J Psychosom Res. 2009 Oct;67(4):289-96
19773021
Epidemiol Rev. 2004;26:63-77
15234948
N Engl J Med. 2009 Jan 8;360(2):129-39
19092145
J Gerontol A Biol Sci Med Sci. 2000 Jul;55(7):M372-7
10898253
J Psychosom Res. 1991;35(6):661-9
1791580
J Behav Med. 1992 Oct;15(5):447-68
1447757
Med Care. 1995 Apr;33(4 Suppl):AS264-79
7723455
N Engl J Med. 2008 Jun 12;358(24):2560-72
18539916
BMJ. 2008 Nov 11;337:a2390
19001484
J Clin Epidemiol. 2009 May;62(5):479-84
18468856
J Gerontol B Psychol Sci Soc Sci. 2004 Mar;59(2):S89-97
15014096