Table 3.
Non-zero activity counts in the ICU, as measured using actigraphy
| n (N=34) | Non-Zero Epochs (N=66,721) | Mean (SD) Non-Zero Activity Levela | Unadjusted Difference (95% CI)b | P value | Adjusted Difference (95% CI)b | P value | |
|---|---|---|---|---|---|---|---|
| Baseline Variables | |||||||
| Age Tertile | |||||||
| 25–50 years old | 12 | 23,811 | 69 (83) | REF | REF | REF | REF |
| 51–65 years old | 11 | 23,338 | 49 (61) | −21 (−40, −2) | 0.01 | −1 (−17, 15) | 0.91 |
| 66–87 years old | 11 | 19,572 | 47 (61) | −23 (−46, 1) | 0.07 | −1 (−24, 21) | 0.90 |
| Gender | |||||||
| Female | 17 | 30,085 | 62 (78) | REF | REF | REF | REF |
| Male | 17 | 36,636 | 50 (62) | −13 (−31, 6) | 0.16 | −15 (−30, 0) | 0.05 |
| Race | |||||||
| White | 21 | 44,500 | 59 (72) | REF | REF | REF | REF |
| Non-white | 13 | 22,221 | 49 (66) | −9 (−27, 9) | 0.32 | −12 (−25, 1) | 0.06 |
| Ambulatory Prior to ICU | |||||||
| No | 2 | 2,985 | 31 (35) | REF | REF | REF | REF |
| Yes | 32 | 63,736 | 57 (71) | 25 (14, 36) | <0.001 | 35 (20, 51) | <0.001 |
| BMI Category | |||||||
| Underweight (BMI <18) | 3 | 8,949 | 85 (97) | 28 (−9, 65) | 0.13 | 6 (−27, 39) | 0.74 |
| Normal (BMI 18–24.9) | 13 | 27,576 | 57 (67) | REF | REF | REF | REF |
| Overweight (BMI 25–29.9) | 9 | 13,123 | 42 (55) | −14 (−30, 1) | 0.07 | −12 (−30, 5) | 0.16 |
| Obese (BMI > 30) | 9 | 17,073 | 48 (64) | −9 (−24, 7) | 0.29 | −4 (−24, 16) | 0.67 |
| Admission Diagnosis Category | |||||||
| Respiratory Failure | 14 | 25,167 | 64 (81) | REF | REF | REF | REF |
| Gastrointestinal | 3 | 5,915 | 56 (66) | −9 (−27, 11) | 0.40 | −9 (−46, 28) | 0.64 |
| Sepsis | 7 | 12,980 | 49 (67) | −15 (−44, 15) | 0.33 | −18 (−39, 4) | 0.11 |
| Cardiovascular | 4 | 10,738 | 58 (63) | −6 (−32, 21) | 0.68 | −11 (−27, 5) | 0.18 |
| Other | 6 | 11,921 | 43 (54) | −21 (−39, −2) | 0.03 | −21 (−44, 3) | 0.08 |
| ICU Variables | |||||||
| Time of day | |||||||
| 06:00–09:59 | - | 12,836 | 59 (76) | REF | REF | REF | REF |
| 10:00–13:59 | - | 11,769 | 63 (83) | 5 (−1.6, 11) | 0.14 | 2 (−3, 7) | 0.45 |
| 14:00–17:59 | - | 14,261 | 61 (75) | 4 (−3, 11) | 0.27 | 2 (−3, 6) | 0.42 |
| 18:00–21:59 | - | 13,443 | 63 (83) | 4 (−5.3, 13) | 0.40 | 0 (−6, 7) | 0.96 |
| 22:00–01:59 | - | 9,329 | 50 (65) | −4 (−13, 5) | 0.38 | −5 (−12, 3) | 0.19 |
| 02:00–05:59 | - | 8,017 | 50 (67) | −6 (−13, 1) | 0.07 | −5 (−11, 2) | 0.16 |
| Average Daily SOFA Tertile | |||||||
| 0.0 – 3.5 | 13 | 30,605 | 58 (71) | REF | REF | REF | REF |
| 3.6 – 7.9 | 11 | 22,809 | 62 (75) | 3 (−19, 26) | 0.77 | −3 (−26, 20) | 0.78 |
| 8.0 – 18.3 | 10 | 12,876 | 39 (57) | −19 (−34, −4) | 0.01 | −22 (−43, −2) | 0.03 |
| Mechanically Ventilated | |||||||
| Never | 23 | 54,114 | 54 (66) | REF | REF | REF | REF |
| Ever | 11 | 12,607 | 63 (87) | 9 (−22, 40) | 0.56 | 0 (−27, 28) | 0.98 |
| Received Continuous Sedation | |||||||
| Never | 27 | 59,101 | 56 (71) | REF | REF | REF | REF |
| Ever | 7 | 7,620 | 49 (64) | −7 (−21, 7) | 0.32 | −9 (−43, 24) | 0.60 |
| Restrained | |||||||
| Never | 31 | 64,220 | 56 (70) | REF | REF | REF | REF |
| Ever | 3 | 2,501 | 38 (62) | −19 (−32, −4) | 0.01 | 2 (−34, 37) | 0.93 |
| All Subjectsc | 34 | 66,721 | 55 (70) | ||||
Abbreviations: ICU = Intensive Care Unit; BMI = Body Mass Index; SOFA = Sequential Organ Failure Assessment
Within-patient standard deviation
Derived using predictive margins of a Poisson regression of non-zero activity counts per epoch, using clustering to account for within-patient correlation of activity levels. All covariates included in multivariable Poisson model.
For reference, a healthy adult undergoing 24-hour actigraphy exhibits 51% non-zero epochs with a mean±SD non-zero activity of 132±141movements, with 138±143 movements from 06:00–09:59, 140±137 from 10:00–13:59, 108±108 from 14:00–17:59, 158±166 from 18:00–21:59, 38±75 from 22:00–01:59, and 143±149 from 02:00–05:59.