The study was approved by institutional review boards at The University of Texas Health Sciences Center – Houston (UTHSC-H) and Baylor College of Medicine (BCM). Participants provided written informed consent for all procedures and received compensation of $20 for each completed assessment.
From March 2004 to August 2006, we recruited participants of 60 years or older. Total recruitment duration, however, was for only 26 months because of two 2-month interruptions: (1) in 8/04, the primary academic affiliation of the project changed from UTHSC-H to BCM, and recruitment resumed in 10/04; (2) recruitment was discontinued from 9/05 through 10/05 because of the significant impact of hurricanes Katrina and Rita in the Houston area.
Most recruitment occurred through Kelsey-Seybold Clinic, a large, multi-specialty medical organization in the greater Houston, Texas, area. For 6 months, participants were also recruited from the BCM Family Medicine Clinic (Houston, TX). Recruitment occurred through patient self-referral and physician referral. Educational brochures were placed in waiting and exam rooms, Health Information Centers, and patient newsletters. Informational letters also were mailed to randomly selected patients in the appropriate age range. Physician referrals were encouraged by presentations at staff meetings, electronic communications with providers, and individual networking.
Referred patients were asked two anxiety screening questions from the PRIME-MD.21
Individuals responding affirmatively were scheduled to review informed consent, collect demographic data, and administer the Mini Mental State Exam 22
and the Structured Diagnostic Interview for DSM-IV
Race and ethnicity were identified by the patient according to categories provided by research staff. These data were collected to facilitate conclusions about generalizability of the data. All interviewers administering the SCID (psychology staff, graduate students, interns and fellows) received extensive training. In addition, all interviews were audio- taped, and a second clinician rated 20%. Kappa coefficients suggested adequate diagnostic agreement: GAD (.64); depression (major depression and dysthymia, .75); social phobia (.81); specific phobia (.64). Patients with a principal or co-principal diagnosis of GAD according to DSM-IV
were included. Patients with Mini Mental State Exam scores less than 24 were excluded, as were patients with active substance abuse, psychosis, or bipolar disorder.
Measures and Data Collection
Primary outcomes assessed worry and GAD severity. Worry severity was measured with the Penn State Worry Questionnaire (PSWQ),24
a 16-item, self-report scale. GAD severity was evaluated with the Generalized Anxiety Disorder Severity Scale (GADSS),25
a six-item, clinician-rated scale. The PSWQ has good psychometrics among older adults26
and is a primary outcome in psychosocial trials of late-life GAD.27, 28
No minimal clinically significant difference (MCID) has been established for the PSWQ, but prior positive clinical trials have demonstrated a change of 8.5 points on the measure following CBT.28, 29
This value was used here to indicate meaningful change. The GADSS also has adequate psychometric support for older adults, 29
although no data from this measure have been reported from clinical trials of GAD. Here, a change of 2.0 points on the GADSS was considered meaningful, given that a difference of 2 points significantly differentiated patients referred to a clinical trial who did and did not meet criteria for GAD.29
Secondary outcomes assessed coexistent anxiety and depressive symptoms and physical/mental health status. Anxiety severity was measured with the Structured Interview Guide for the Hamilton Anxiety Scale (SIGH-A).30
The SIGH-A has adequate psychometric support among older adults.31
Severity of depressive symptoms was measured with the Beck Depression Inventory, Second Edition (BDI-II).32
The BDI-II has been used with community samples of older adults33
and older adults with anxiety.20
Health quality of life was measured with the 12-item Medical Outcomes Study Short Form, which yields two summary scores developed from the original measure,34
the mental (MCS) and physical component scores .35
Reliability and validity have been established in older adults.36
Medication use was assessed with patient self-report questions about the type and frequency of medications used over the prior 3 months.37, 38
Medications classified as antianxiety
(benzodiazepine, buspirone, or other) or antidepressant
(selective serotonin reuptake inhibitor, nonselective serotonin reuptake inhibitor, tricyclic antidepressant, or other) were considered. Patients also were asked to report the number of outpatient medical and mental health visits and to indicate whether they had spoken with their doctor about emotional issues or received a mental health referral over the past 3 months.
All outcome measures were administered via telephone by a Masters- or Postdoctoral-level independent evaluator (IE) unaware of treatment assignment. (Given the nature of the intervention and control conditions, patients and therapists were not blind to study condition.) IEs readministered outcome evaluations at 3 months (post-treatment) and at 3-month intervals over a 12-month follow-up. The third author (DN) held regular calibration meetings with IEs. All assessment sessions were audiotaped, and a random 10% were reviewed by a different independent rater. Interrater agreement was excellent (SIGH-A31
). Psychometric properties for telephone-based assessment instruments were comparable to in-person versions.39
Five experienced therapists provided CBT in up to 10 individual sessions over 12 weeks. Therapists were three Masters-level therapists with at least 2 years of prior CBT experience, one pre-doctoral intern with over 3 years of CBT-anxiety experience, and one post-Bachelor’s-level therapist (PW) with 5 years experience in CBT for late-life anxiety.
Therapist training involved treatment of two nonstudy patients, with competence and adherence ratings of at least 6 on a 0 to 8 scale. CBT included education and awareness, motivational interviewing, relaxation training, cognitive therapy, exposure, problem-solving skills training, and behavioral sleep management.40
Brief telephone booster sessions were offered at 4, 7, 10, and 13 months. Sessions were audiotaped, and 20% were rated by two independent treatment-integrity experts, Drs. Derek Hopko and Gretchen Diefenbach, who co-authored the treatment manual upon which CBT in this study was based. Neither participated in the study in other ways. Ratings suggested excellent adherence (7.7, SD = 0.55; range = 0 to 8) and competence (7.3, SD = 0.67; range = 0 to 8).
Patients in EUC were called biweekly during the first 3 months of the study by the same therapists to provide support and ensure patient safety. Calls last approximately 15 minutes. Therapists reminded patients to call project staff if symptoms worsened and suggested contacting their primary care physician (PCP) for medical problems. A supervisor (MS, NW, MK) and the patient’s PCP were notified of patients needing immediate psychiatric care. All calls were audiotaped, and 20% (n = 93) were reviewed by the first author. Only three protocol deviations were identified.
CBT patients completed an average of 7.4 sessions in the primary care clinic (SD
= 1.91). EUC participants received an average of 4.3 telephone check-ins (SD = 1.26). After the first session in each condition, patient expectancy was assessed with a single item asking patients to rate the amount of improvement they expected (0%= none; 100%=complete improvement).41
Communication with the PCP occurred via notes filed in the research section of the written medical record. Initial notes indicated diagnoses assigned and inclusion/exclusion status. For excluded patients, potential referrals were provided to the PCP and the patient. For included patients, notes encouraged care as usual and indicated whether patients had received a CBT session or an EUC contact.
Patients were randomized initially according to a 1:1 ratio within blocks of 10 to CBT or EUC. More patients were randomized to CBT (n=70) than EUC (n=64). Inspection of data at study mid-point (50% recruitment completed) revealed a disproportionate random assignment of Hispanic patients to EUC. A stratified randomization schedule was then instituted for Hispanic patients, with 80% assignment to CBT, to ensure equivalence across groups. Non-Hispanic patients were maintained on the original 1:1 randomization schedule. The randomization scheme was generated by the study statistician (HR) using a random number generator; and assignments were placed in numbered, sealed envelopes. Upon completion of baseline assessment, a study research assistant opened the next envelope in sequence and assigned the participant to a treatment condition.
Before conducting outcome analyses, we compared patients in the CBT and EUC subgroups on pretreatment demographic variables, clinical characteristics, and medication utilization, using Chi-square analyses and t-tests. Primary analyses then examined post-treatment outcomes by comparing group differences at 3 months, using a between-groups analysis of covariance (ANCOVA), with pretreatment assessment as the covariate. Initial analyses were intent-to-treat (ITT), using the SAS multiple imputation procedures, Proc MI and MIANALYZE, version 9.2, to address missing data. Another set of analyses repeated these comparisons only with observed data, using random regression methods (i.e., completer analysis using SAS’s Proc Mixed). Secondary analyses examined long-term outcomes with a repeated-measures–analysis-of-covariance procedure (SAS’s Proc Mixed), again with the pretreatment assessment as the covariate. To control for multiple comparisons within clusters of outcomes (primary outcomes, coexistent anxiety-depression, health quality of life), each of which included two variables, critical alpha was set at p< .025. All significance testing was two-sided.
Because three couples participated in the study (with both partners randomized to the same condition; n = 2 in CBT, n = 1 in EUC), all analyses were rerun with one individual from each couple randomly removed to assess the possible influence of correlated data. These analyses did not result in different findings and therefore are omitted. Finally, changes in the use of antidepressant and antianxiety medications during the trial were examined with Chi-square analyses, and exploratory analyses examined the role of expectancies in predicting outcome.
Treatment response was defined by meaningful change on the PSWQ and GADSS, as defined earlier (PSWQ=8.5; GADSS=2.0); see Primary Outcomes). The proportions of patients classified as treatment responders according to these cut-offs were determined at 3 and 15 months. Group differences in ITT and completer samples were tested, using Chi-square analyses. For ITT analyses, patients with missing data were classified as nonresponders.
Power calculations were based on the PSWQ, which is a primary outcome in CBT trials of late-life GAD. Median standard deviation across these trials is 10.1. This figure was considered in combination with an expected moderate effect size (d=.60, minimal detectable difference = 6.2), desired 80% power, and alpha of .025. Given these parameters and a potential 30% attrition, our goal was to include 150 participants so that 53 per group would be available for analysis. The included sample (n = 148) was 99% of this target. The randomized sample (n = 70 CBT, n = 64 EUC) and the completer sample (n = 115) both exceeded the required 53 per group.