Table 2.
Modified Intention-to-Treat Analysis for Primary and Secondary Sleep and Pain Outcomes for the Entire Sample and for the Subgroup Analysis of Participants with Severe Pain at Baseline
| Measure | Baseline | Postintervention | 9-Month Follow-Up | A Baseline to 9 Months3 | Treatment Effect3 | Omnibus P-Valuec |
Pair-Wise P-Valued |
Unadjusted Effect Size |
|||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N | Mean (95% CI) |
N | Adjusted Mean (95% Cl)b |
N | Adjusted Mean (95% Cl)b |
Adjusted Mean A (95% Cl)b |
Estimate (95% Cl)b |
||||
| Entire sample | |||||||||||
| Insomnia severity | |||||||||||
| EOC | 123 | 11.51 (10.61–12.42) |
122 | 10.39 (9.36–11.42) |
120 | 10.18 (8.96–11.40) |
−1.35 (−2.57 to −0.13) |
N/A | <.001 | N/A | |
| CBT-P vs EOC | 122 | 11.85 (11.01–12.69) |
117 | 10.53 (8.69–12.36) |
111 | 10.31 (8.33–12.29) |
−1.21 (−3.19–0.76) |
0.13 (−0.89–1.16) |
.80 | 0.08 (−0.11–0.26) |
|
| CBT-PI vs EOC | 122 | 11.20 (10.28–12.13) |
113 | 8.50 (6.77–10.22) |
108 | 8.28 (6.43–10.13) |
−3.24 (−5.09 to −1.39) |
−1.89 (−2.83 to −0.96) |
<.001 | −0.40 (−0.59 to −0.21) |
|
| CBT-PI vs CBT-P | −2.03 (−3.01 to −1.04) |
<.001 | −0.48 (−0.67 to −0.29) |
||||||||
| Pain severity | |||||||||||
| EOC | 123 | 4.13 (3.86–4.41) |
122 | 4.08 (3.68–4.48) |
120 | 3.96 (3.45–4.48) |
−0.38 (−0.90–0.13) | N/A | .54 | N/A | |
| CBT-P vs EOC | 122 | 4.34 (4.06–4.62) |
117 | 4.16 (3.64–4.69) |
111 | 4.04 (3.44–4.65) |
−0.30 (−0.91–0.30) |
0.082 (−0.21–0.38) |
N/A | 0.13 (−0.05–0.32) |
|
| CBT-PI vs EOC | 122 | 4.57 (4.30–4.84) |
113 | 3.99 (3.45–4.52) |
108 | 3.87 (3.26–4.48) |
−0.48 (v1.09–0.13) |
−0.095 (−0.37–0.18) |
N/A | 0.04 (−0.15–0.23) |
|
| Sleep efficiencye | |||||||||||
| EOC | 118 | 83.01 (81.40–84.63) |
115 | 81.02 (79.11–82.93) |
107 | 80.85 (78.70–83.00) |
−1.74 (−3.88–0.41) |
N/A | .006 | N/A | |
| CBT-P vs EOC | 114 | 83.09 (81.49–84.70) |
101 | 83.93 (80.85–87.00) |
93 | 83.76 (80.61–86.91) |
1.17 (–1.98–4.33) |
2.91 (0.85–4.97) |
.006 | 0.35 (0.15–0.54) |
|
| CBT-PI vs EOC | 112 | 81.62 (79.93–83.32) |
96 | 83.66 (80.05–87.28) |
94 | 83.49 (79.74–87.25) |
0.91 (−2.85–4.66) |
2.64 (0.44–4.84) |
.02 | 0.31 (0.11–0.51) |
|
| CBT-PI vs CBT-P | −0.26 (−2.82–2.29) |
.84 | −0.04 (−0.25–0.16) |
||||||||
| AIMS symptom subscale | |||||||||||
| EOC | 123 | 6.10 (5.71–6.50) |
122 | 6.70 (6.32–7.07) |
120 | 6.86 (6.41–7.31) |
0.84 (0.38–1.29) |
N/A | .53 | N/A | |
| CBT-P vs EOC | 122 | 5.90 (5.49–6.31) |
117 | 6.64 (6.02–7.26) |
111 | 6.80 (6.12–7.48) |
0.78 (0.10–1.46) |
−0.06 (−0.39–0.28) |
N/A | −0.10 (−0.28–0.08) |
|
| CBT-PI vs EOC | 121 | 6.06 (5.68–6.44) |
112 | 6.90 (6.17–7.64) |
107 | 7.06 (6.32–7.81) |
1.04 (0.29–1.79) |
0.20 (−0.26–0.66) |
N/A | 0.10 (−0.09–0.29) |
|
| Participants with severe pain at baseline | |||||||||||
| Insomnia severity | |||||||||||
| EOC | 41 | 13.51 (11.94–15.08) |
41 | 12.25 (10.05–14.46) |
40 | 12.14 (9.65–14.63) |
–0.79 (–3.28–1.70) |
N/A | .01 | N/A | |
| CBT-P vs EOC | 43 | 12.67 (11.11–14.24) |
42 | 11.96 (8.12–15.80) |
41 | 11.84 (7.81–15.88) |
–1.08 (–5.12–2.95) |
−0.29 (−2.36–1.77) |
.78 | −0.17 (−0.45–0.11) |
|
| CBT-PI vs EOC | 52 | 12.67 (11.25–14.09) |
48 | 9.55 (5.41–13.68) |
44 | 9.43 (5.18–13.68) |
−3.50 (−7.75–0.75) |
−2.71 (−4.91 to −0.51) |
.02 | −0.49 (−0.74 to −0.24) |
|
| CBT-PI vs CBT-P | −2.42 (−4.15–0.68) |
.006 | −0.32 (−0.59 to −0.06) |
||||||||
| Pain severity | |||||||||||
| EOC | 41 | 5.89 (5.67–6.12) |
41 | 5.42 (4.69–6.16) |
40 | 5.29 (4.38–6.20) |
−0.69 (−1.60–0.22) |
N/A | .27 | N/A | |
| CBT-P vs EOC | 43 | 6.07 (5.78–6.36) |
42 | 5.26 (4.15–6.37) |
41 | 5.13 (3.96–6.30) |
−0.85 (−2.02–0.32) |
−0.16 (−0.68–0.37) |
N/A | 0.03 (−0.26–0.33) |
|
| CBT-PI vs EOC | 52 | 5.98 (5.77–6.19) |
48 | 4.98 (3.83–6.12) |
44 | 4.84 (3.64–6.04) |
−1.14 (−2.34 to −0.06) |
−0.44 (−1.00–0.11) |
N/A | −0.18 (−0.46–0.09) |
|
| Sleep efficiencye | |||||||||||
| EOC | 41 | 81.24 (78.34–84.14) |
41 | 79.26 (75.86–82.66) |
36 | 78.88 (75.44–82.32) |
−1.83 (−5.27–1.61) |
N/A | .004 | N/A | |
| CBT-P vs EOC | 40 | 79.92 (76.19–83.65) |
32 | 84.70 (79.76–89.64) |
32 | 84.32 (79.75–88.90) |
3.62 (−0.96–8.19) |
5.45 (1.56–9.33) |
.006 | 0.50 (0.20–0.80) |
|
| CBT-PI vs EOC | 46 | 80.91 (78.36–83.46) |
40 | 82.94 (77.22–88.66) |
36 | 82.56 (76.43–88.70) |
1.86 (−4.28–7.99) |
3.69 (0.72–6.66) |
.01 | 0.44 (0.19–0.69) |
|
| CBT-PI vs CBT-P | −1.76 (−6.10–2.58) |
.43 | −0.09 (−0.37–0.19) |
||||||||
| AIMS symptom subscale | |||||||||||
| EOC | 41 | 4.88 (4.26–5.49) |
41 | 5.60 (4.75–6.44) |
40 | 5.87 (4.89–6.86) |
1.01 (0.02–2.00) |
N/A | .79 | N/A | |
| CBT-P vs EOC | 43 | 4.67 (3.95–5.39) |
42 | 5.64 (4.32–6.97) |
41 | 5.92 (4.52–7.32) |
1.06 (−0.34–2.45) |
0.05 (−0.60–0.69) |
N/A | −0.07 (−0.36–0.22) |
|
| CBT-PI vs EOC | 52 | 5.02 (4.45–5.58) |
48 | 5.87 (4.35–7.40) |
44 | 6.15 (4.55–7.75) |
1.29 (−0.31–2.88) |
0.28 (−0.55–1.10) |
N/A | 0.06 (−0.21–0.32) |
|
CI = confidence interval; N/A = not applicable; AIMS = Arthritis Impact Measurement Scale.
Decrease indicates improvement for insomnia severity and pain severity; increase indicates improvement for sleep efficiency and arthritis symptoms.
Means and treatment effect estimates adjusted for baseline values of relevant outcome, age, depression, modified Mini-Mental State Examination score, analgesic use, hypnotic use, an indicator of whether the outcome was measured at 9 months, and the clinic at which the intervention was delivered.
P-value for omnibus Wald test employing both posttreatment visits (postintervention and 9 months) controlled for baseline values, depression, cognitive status, opioid and hypnotic medication use, and clinic.
Pair-wise P-values for cognitive–behavioral therapy for pain (CBT-P) minus education-only control (EOC), cognitive–behavioral therapy for pain and insomnia (CBT-PI) minus EOC, and CBT-PI minus CBT-P. P-values correspond to a two-sided test of the null hypothesis that the difference between the two means is 0.
Sample size differs for sleep efficiency analysis because some actigraphic data were lost because of recording failure; this equipment failure was completely at random. Participants were required to have a minimum of 3 nights of actigraphy data to be included in the analysis (range 3–7 days, mean 6.88 at baseline, 6.83 at posttreatment, and 6.89 days at 9-month assessments).