Review Article

The Impact of Pain Assessment on Critically Ill Patients’ Outcomes: A Systematic Review

Table 1

Summary of study characteristics and main outcomes (APACHE: acute physiology and chronic health evaluation; BPS: behavioral pain scale; CPOT: critical pain observation tool; HCP: health care professionals; ICU: intensive care unit; IQR: interquartile range; LOS: length of stay; MV: mechanical ventilation; NA: not assessed; NRS: numerical rating scale; NS: nonsignificant; pts: patients; RASS: Richmond Agitation sedation Scale; SOFA: sequential organ failure assessment).

Authors, year (country)Study design/aimStudy setting
(ICU type)
Sample size ()
Type of scale/instrument used and
specifics of nurses’ HCP’s training on use of scales
Severity of illness measures
Outcome: level of pain/agitation and documentation of pain assessmentsOutcome: use of analgesics and sedativesOutcome: ICU length of stay (LOS) in days (mean, SD)Outcome: adverse events/complicationsOutcome: hospital length of stay in days (mean, SD)Outcome: duration of mechanical ventilation in days (mean, SD)Outcome: days off ventilatorOutcome: patient satisfactionOutcome:
mortality rate

Rose et al., 2013 [9]
(Canada)
Preexperimental 2-group pretest-posttest design
(preimplementation phase: 5 months, postimplementation: 5 months)
Aim: to compare preimplementation to postimplementation practice and outcomes
2 closed ICUs
Mixed ICU (medical/surgical/trauma) + cardiovascular ICU
( before implementation; after implementation)
CPOT
All nurses received special training (video demonstration and instruction on use of CPOT)
Severity of illness measures: SOFA median (IQR)
6 (3–8) for mixed ICU pts before implementation and 4 (3–6) after implementation
8 (5–11) for cardiovascular ICU pts before implementation 8 (6–11) for Cardiovascular ICU pts after implementation
Proportion of pain assessment intervals with pain assessment documented increased
from 15% to 64% () 
(cardiovascular unit);
from 22% to 80% () (mixed ICU)
Median total dose of opioid analgesics decreased from 5 mg to 4 mg () (cardiovascular ICU) and increased from 27 mg to 75 mg to mixed ICU
Median total dose of benzodiazepines decreased from
12 mg to 2 mg () (cardiovascular unit); remained unchanged (mixed ICU)
Median LOS ICU in Cardiovascular ICU decreased from 2.0 (IQR, 1.0–5.0) days to 1.8 (IQR, 1.0–3.0) days ();
in mixed ICU (median, 5.9; IQR, 2.9–13.6 days before
and median, 7.0; IQR, 5.0–14.7 days after)
NANAIn the cardiovascular ICU median was 0.6 (IQR, 0.3–0.8) days before CPOT and 0.5 (IQR, 0.3–0.8)
days after;
in the mixed ICU median was
3.9 (IQR, 1.4–10.7) days before implementation and
5.9 (IQR, 3.0–9.1) days after
NANANA

Radtke et al., 2012 [10]
(Germany)
Preexperimental 3-group pretest-posttest design
(preimplementation phase (retrospective data collection): 2 months,
postimplementation (prospective): 2 months) with 1-year follow-up
Aim: to compare the effectiveness of two training strategies standard training for pain assessment sedation and agitation versus modified extended training
3 surgical ICUs

( before implementation; after implementation; follow-up)
NRS, BPS, RASS
Standard training for nurses and physicians included lectures, movie, hand-outs one to one instruction
Extended modified training including establishment of local support team
Severity of illness measures: APACHE II, SOFA
Frequency of monitoring per patient and day
for pain (NRS, BPS)
ICU 1: pretest 2.3 (1.4–3.2); posttest 4.0 (3.0–5.6);

follow-up 4.6 (3.2–5.8);
ICU 2: pretest 1.8 (1.3–2.2); post-test: 2.2 (1.8–2.6); p2.6 (1.5–3.5)  
Follow-up: 2.0 (1.7–3.0);
ICU 3: Pretest: (0.0–0.0); post-test: (0.0–0.0);  
= ns
Follow-up: 2.6 (1.5–3.5);
N/A
Administration of analgesics decreased from 3.87 (SD = 2.59); to 2.47 (SD = 2.56)
ICU 1: pretest 18 (32); posttest 15 (20); follow-up 14 (21);
ICU 2: pretest 8 (7); posttest 7 (7); follow-up
4 (3);   
ICU 3: pretest 9 (8); posttest 7 (8); follow-up 9 (11);
N/A
Number of complications mean decreased from 4.53 (SD = 5.19) to 1.87 (SD = 1.69)
N/AICU 1: pretest 355 (697); posttest 281 (448); follow-up 265 (495)
ICU 2: pretest 7 (12); posttest 5 (8); follow-up 4 (9);
ICU 3: pretest 117 (196); posttest 83 (154); follow-up 149 (244)
N/AN/AOn ICU 2, the measurement of NRS/BPS was associate
with reduced mortality (odds ratio (pain) = 0.365
95% CI: 0.147–0.866,

Arbour et al. 2011 [11]
(Canada)
PILOT preexperimental 2-group pretest- posttest design
(preimplement trauma ICU
medical files: 15 before implementation and 15
after implementation of the CPOT implementation phase: 1 year, postimplementation: 6 months)
Aim: to explore the impact of the
implementation of the CPOT on
pain management and clinical outcomes in mechanically
ventilated trauma intensive care unit patients
Trauma ICU
medical Files: 15 before implementation and 15
after implementation of the CPOT
CPOT
Nurses were taught how to
use the CPOT through a training session
and practiced its scoring method with patients’
videotapes
Severity of illness measures: APACHE II
Frequency of pain assessments mean increased from 4.33 (SD = 2.32) to 12.33 (SD = 4.69)
No of pain episodes mean increased from 1.13 (SD = 1.13); post implementation 4.27 (SD = 2.09)
Morphine equianalgesic dosage mean decreased from 15.60 (SD = 11.35); to 9.37 (SD = 8.94)

Administration of sedatives mean decreased from 1.33 (SD = 2.66) to 0.60 (SD = 0.83)
Decreased from 10.53 (SD = 11.16) to 5.33 (SD = 5.86)
N/A(Days) mean decreased from 6.93 (SD = 7.37) to 4.00 (SD = 5.0)N/AN/AN/A

Gélinas et al. 2011 [12]
(Canada)
Preexperimental 2-group pretest- posttest design
(preimplementation phase: ×3 months, implementation phase: ×3 months post-implementation: ×3 months and 12 months)
Aim: to evaluate the implementation of the
CPOT on pain assessment and management nursing
practices with nonverbal critically ill patients
ICU
ICU nurses
medical files
(30 before implementation, 30
3 months after implementation,
30 12 months after implementation
CPOT
All nurses were trained in the use of CPOT
Severity of illness measures: NR
Reports of pain assessments increased from 3,00 (median) before implementation to 10.50 at 3 months and 12,00 at 12 months after implementation
Documentation of behaviors indicative of the presence of pain increased from 0,00 (median) before implementation to 1,00 at 3 months and 2,00 at 12 months after implementation. (, )
Reports of pain reassessments postintervention frequency (%) increased from 14 (9.92%) before implementation to 28 (43.1%), 3 months and 26 (59.1%), 12 months after implementation
Number of analgesic bolus administered (median) decreased from 3,00 before implementation to 1,00 at 3 months and 0,5 at 12 months after implementation (,
)
Total of equianalgesic doses (median) was similar in the preimplementation group (1,50) and in the 3
months after implementation group (2.25) but was smaller (0,25) at 12 month after implementation
Sedatives:
significant
decrease in the number of propofol bolus (,
) and dose (mg) (, ) administered
postimplementation
N/AN/AN/AN/AN/AN/AN/A

Topolovec-Vranic et al. 2010 [13]
(Canada)
Preexperimental retrospective 2-group pretest-posttest design
preimplementation phase: ×4 weeks, postimplement ×4 weeks
Aim: to evaluate the
effect of the NVPS implementation
Trauma and neurosurgical ICU
medical charts of noncommunicative patients (20 preimplementation and 20 after implementation) and medical charts of communicative patients (13 before implementation and 13 after implementation)
For the patients satisfaction survey patients (25 before and 39 after the implementation of NVPS)
NVPS
patient satisfaction survey (modified of the APS-POQ)
Nurses received in-service
training for 2 weeks (small group presentations, Pocket education cards)
Severity of illness measures: NR
For noncommunicative patients total number of documented pain assessments increased from 457 to 584 after the implementation; the proportion of numerical assessments increased from 131 [29%] to 297 [51%];
and the number of assessments per patient per ICU day increased from 2.2 to 3.4;
For communicative patients total number of documented pain assessments increased from 90 to 120; the numerical assessments increased from 8 (9%) to 61 (51%);
A trend toward an increase in the number of assessments per patient ICU day was noted (before 6.0, after 10.3;
)
Patients’ ratings of their “pain right now” on a scale from 0 to 10 did not differ from before (4.3) to after (3.9) implementation
patients reports for the worst pain you had during your ICU stay were lower after implementation
(7.2) than before implementation (8.5);
The proportion of patients reported the intensity of their pain during their ICU stay as
severe was reduced from 55% to 35%
No differences were found in the type of opioid
analgesics administered or the amount of medication
(morphine equivalents) given per patient or per
patient per ICU day when compared from before to after implementation
For noncommunicative patients, days in ICU (standard error of the mean) decreased from 11.9 (2.1) to
10.7 (1.7);
after implementation
For Communicative patients from
1.0 (0.15) to 1.1 (0.14);
after implementation
N/AN/AN/AN/AHigh levels of satisfaction with no significant difference between the groupsN/A

Payen et al. 2009 [6]
(France)
Concurrent 2-group comparative
Both groups followed up until death or ICU discharge or for 30 days in the ICU
Aim: to investigate whether an association exists between pain assessments, MV duration, and duration of ICU stay in mechanically ventilated patients receiving
analgesia on day 2 of their ICU stay
43 ICUs multicentre

Mechanically ventilated patients who received analgesia on day 2;  pts not assessed for pain versus patients assessed for pain on day 2
BPS, VAS, Harris Scale, NRS, verbal descriptor scale
Severity of illness measures: SAPS II
Patients assessed for pain were More likely to be assessed for sedation; 91% versus 30%; The group of patients who were assessed for pain
(1) were more likely to receive fentanyl (%) 184 (36) versus 179 (28); ; more dose of sufentanil median (IQR), μg 7.6 (4.2–10.9) versus 5.1 (2.8–7.6); and
Less dose of remifentanil, 98 (64–145) versus 149 (77–214);
(2) more patients were treated with nonopioids and were more likely to receive multimodal analgesia; ,
and dedicated procedural pain assessment and treatment
Patients who were assessed for pain received fewer hypnotics, (%); 384 (75) versus 544 (86); and lower
daily doses of midazolam 295 (57) versus 411 (65);

Neuromuscular Blocking agents were reduced in patients with pain assessment 35 (7) versus 83 (13);
Patients who were assessed for pain had shorter duration of ICU LOS (13 versus 18 days)
Ventilator-acquired pneumonia, (%) for those not assessed 117 (24) versus 66 (16)

Thromboembolic events, n (%) for those not assessed 13 (3) versus 10 (2);
Gastroduodenal hemorrhage n (%) for those not assessed 8 (2) versus 4 (1);
Central venous catheter colonization, n (%) for those not assessed 28 (6) versus 19 (5);
N/APatients who were assessed for pain had shorter duration of MV, 8 versus 11 days; Increased odds of weaning from ventilator odds ratio 1.40; 95% confidence interval 1.00–1.98N/APatients not assessed for pain; (22%) versus patients assessed for pain; (19%)
Unadjusted Odds Ratio (95% CI); 0.91
(0.58–1.43)

Williams et al. 2008 [14]
(Australia)
Preexperimental 2-group pretest- posttest design
(preimplementation phase: 6 m, postimplementation: 6 m)
Aim: To evaluate outcomes before and after introduction
of scales for analgesia and sedation
General closed ICU
ventilated patients (369 patients before and 400 patients after
implementation)
BPS, RASS
Education on the use of scales was provided to all staff
Severity of illness measures: APACHE II
N/AFor patients who had complete sedation data, the proportion
of patients receiving sedatives with or without analgesics during their admission was greater in the after group (88%) than in the before group (57%);
It was similar between the groups: 2.3 days before implementation versus
2.6 days after implementation; no significant result ()
Incidence of unplanned extubation decreased after implementation (2 unplanned extubations after implementation
versus 7 before implementation, )
N/AIt did not change significantly after the scales were introduced
(median, 24 versus 28 hours)
For patients who received
mechanical ventilation for 96 hours or longer (24%), mechanical
ventilation lasted longer after implementation of the scales
()
N/AN/AN/A

Chanques et al. 2006 [15]
(France)
Preexperimental prospective 2-group pretest-posttest design
(preimplementation phase: 21 weeks, postimplementation: 29 weeks)
Aim: to measure the impact of implementation of the
systematic evaluation of pain and agitation by nurses
Medical-surgical ICU
ICU pts control group, ; intervention group,
BPS, NRS, RASS
A period of 4 wks of training for physicians and residents who received an oral education and written support based vigorous
Assessment and treatment of pain and/or agitation Nurses were trained individually at the bedside to evaluate pain and agitation levels
Severity of illness measures: SAPS II
The median observation rate of systematic evaluation of pain and agitation was higher in the intervention group; 75.0 (62.0–90.0) for pain and 77.1 (70.0–90.8) for agitation than the control group 58.6 (40.0–76.7) for pain and 64.0 (50.0–81.7) for agitation;
The incidence of pain and agitation was significantly lower in the intervention group than the control group: 63 versus 42% () for pain and 29 versus 12% () for agitation
The incidence of severe pain and severe agitation were significantly lower in
the intervention group: 36 versus 16% () for pain
and 18 versus 5% () for agitation
Among pain and agitation events, the rate of severe pain events evaluated by an
NRS level >6 and the rate of severe agitation events evaluated by a RASS level
>2 was significantly lower in the intervention group: 57 of 176 versus 24 of 168 events () and 42 of 82 versus 9 of 31
events (), respectively
Among the analgesic and sedative drugs used during the two phases, tramadol was the only drug used significantly more frequently in the intervention group (16 versus 27%, )
There was no
significant difference among drugs used for continuous sedation in the two groups: Midazolam, propofol, or either was used for continuous sedation, respectively, in 87%, 7%, and 6% in control
group versus 74%, 16%, and 10% in the intervention group ()
Fentanyl, morphine, or either was used for continuous sedation, respectively, in 89%, 2%, and 9% in control group versus 80%, 8%,
and 12% in the intervention group ()
No significant
difference in median length of stay in ICU between the two groups 8.5 (4.0–14.7) in the control versus 7.0 (4.0–13.0) in the intervention group;
Marked decrease in nosocomial
infections rate in the intervention group; 11/130 (8) versus control group 17/100 (17);
N/AMarked decrease in the total duration of ventilation, hrs; 120 (48–312) in the intervention group versus 65 (24–192) in the control group; N/AN/ANo significant
difference in
mortality in ICU between the two groups 12 (12) in the control versus 19 (15) in the intervention group;

Voigt et al. 1995 [16]
(USA)
Preexperimental 2-group pretest- posttest design
Pre- and postimplementation phase duration not reported
Aim: to examine the impact of nurses’ use of a standardized pain flow sheet to document pain assessments and pharmacologic management on patient -reported pain intensity
Surgical Heart Unit
( preimplementation group and postimplementation group)
Standardized pain flow sheet
NRS
Severity of illness measures: NR
The distribution of pain intensity scores in intervention group was shifted to lower values relative to those in control group for Average pain (, ), now pain (, ) and least pain (, )
Documentation of pain was greatly improved in intervention group for the operative day (, ) for day 1 (, ) and for day 2 (, )
The intervention group received more pain medications, morphine equivalents-on day 1 than the control group (, )
No statistical difference was found on the operative day (, ) day 2 (, ) or for the total amount given while in the ICU (, )
No significant difference between the groups (, )N/AN/ANo significant difference between the groups (, )N/AN/AN/A

Meehan et al. 1995 [17]
(USA)
Preexperimental 2-group pretest- posttest design
(retrospective phase ×2 months
prospective phase from 1992 to 1993)
Aim: to examine nursing practice regarding analgesic administration and measure pain intensity and patient satisfaction with pain management practices
Cardiothoracic ICU
(retrospective charts review and concurrent prospective sample of 51 patients)
VAS, pain relief satisfaction questionnaire
Severity of illness measures: NR
The mean VAS score was only available for the prospective group (3.8–4.59)Amount of time analgesia was held before extubation was decreased in prospective group (5.41 hrs in retrospective group versus 4.25 hrs in prospective)
A greater number of patients in the prospective group received procedural analgesia (64%)
The prospective group received significantly more analgesia through day 3 than retrospective group () whereas retrospective group received more analgesia later in their ICU stay ()
In the prospective group more patients received hypnotics (statistics not available)
76% of the prospective group transferred on day 2 or sooner from the ICU versus 54% in the retrospective groupN/AN/ANo difference in time of extubation between the two groups: (retrospective group mean of 16.11 hrs versus 14.1 hrs in the prospective group)N/A96% of the prospective group experienced effective pain management
No data were available for the retrospective group
N/A