Running Head: PAIN CONTRACTS 1

Pain Contracts in Post-Operative Joint Patients

PAIN CONTRACTS 2

Pain Contracts in Post-Operative Joint Patients

Problem Overview

Introduction to the Problem

Pain is a compound, subjective feeling which encompasses multiple domains. In fact, 77-

98% of patients experience post-operative pain, with up to 50% reporting moderate pain (Lin,

2011; Wong, Lin, Lee, & Liu, 2012). Pain control directly correlates with functional status. If

patients have uncontrolled pain, they are unable to fully participate in physical and/or

occupational therapy. This results in a longer hospitalization and ultimately, a longer recovery

period. Greater physical independence comes with early discharge and home rehabilitation,

therefore proper pain control is necessary for the best patient outcomes (Murphy, et al., 2011).

Although nutritional status, hemoglobin levels, pre-operative status, and other factors

play a role in recovery, pain control is essential for functionality (Murphy, et al., 2011). By

initiating pain contracts in the post-operative hip and knee total arthroplasty patients, healthcare

providers can have a better understanding of individual pain goals and expectations in the post-

operative period. As an easy, inexpensive intervention, pain contracts give patients a feeling of

control in their care, as well as the ability to verbalize any concerns in regards to pain control.

This would allow for increased control in the immediate post-surgical period.

Review of the Literature

Many studies have been conducted implementing non-pharmacological interventions in

an effort to increase pain control in post-operative patients. It is understood the sympathetic

nervous system (SNS) is involved in pain as evidenced by changes in blood pressure and pulse in

response to painful stimuli (Editorial, 2011). However, much less information is available

regarding the autonomic nervous system’s (ANS) role in pain response. Studies have shown

PAIN CONTRACTS 3

stimulation of the vagus nerve is “capable of reducing acute pressure pain but not thermal or

mechanically induced pain” (Editorial, 2011, p. 542). More research is needed to fully

understand the role of the ANS in acute pain development and the span for analgesic treatment

(Editorial, 2011). Pain is a multi-modal feeling; it is important to understand its physiological

effect on the body before delving in to its subjective side.

Payne, et al. (2010) looked at incorporating pain contracts or agreements in patients with

chronic pain to reduce opioid abuse. Interestingly, “the number of patients with chronic pain

exceeds those with diabetes, heart disease, and cancer combined” (Payne, et al., 2010, p. 5).

Unfortunately, it is difficult to determine how many of these patients with chronic pain abuse the

use of opioid therapy for pain relief. In this study, the pain contracts were used for the provider

to explain his/her expectations of the patient and the conditions in which the provider will

prescribe opioid medication (Payne, et al., 2010). A positive outcome could not be reached in

this particular instance as many believed the initiation of a pain contract/agreement in this study

was discriminatory and resulted in a lack of trust between patient and provider. However, in the

present study, pain contracts were used to incorporate the patient into the care plan in an effort to

allow healthcare providers to fully understand expectations and goals in regards to pain

management as verbalized by the patient.

Murphy, et al. (2011) studied the effects of dispensing information booklets to hip

fracture patients in the early post-operative period to improve early mobilization. Similar to

initiating a pain contract, educating patients via an information booklet allows them to become

more involved in their care and rehabilitative care. This study contained a control group which

received usual care and two experimental groups. One group received an information booklet

that contained basic post-operative information, while the other group’s booklet contained more

PAIN CONTRACTS 4

detailed, comprehensive information (Murphy, et al., 2011). The researcher’s theory proposes the

earlier functional status is regained, the more economically friendly the hospitalization

expenditure is, and the rate of re-hospitalization decreases (Murphy, et al., 2011). Although the

improvements in mobility status changed, they did not reach statistical significance. However, it

should be noted that the experimental group who received a booklet containing basic information

had the greatest improvements (Murphy, et al., 2011).

The ability of energy, via thermal therapy, to increase patient’s pain thresholds in post-

operative total knee arthroplasty patients was studied (Wong, et al., 2012). A sample size of 41,

with 21 in the control group and 20 in the thermal therapy experimental group found no

statistical significance between the groups in pain measurement (Wong, et al., 2012). Although,

the results were not statistically significant, decreases in pain measurement were present.

Music therapy is one of many non-pharmacological interventions that have been

implemented in post-operative patients with pain in an effort to reduce the overall pain

experience. Research has shown that music causes a decrease in heart and respiratory rates,

enhances relaxation, and reduces anxiety while improving mood (Vaajoki, Pietila, Kankkunen, &

Vehvilainen-Julkunen, 2011). However, no statistical significance was found overall in pain

intensity between the experimental and control groups at any of the studied post-operative dates

in 168 subjects (Vaajoki, et al., 2011).

Lin (2011) looked at the effects of relaxation therapy for patients undergoing joint

replacement surgery. Because surgery is a stressful event for most patients, anxiety is a pre-

operative and post-operative concern for those deals with the patient’s care. If the patient is

overly anxious, then a decline in overall health status can occur prolonging the recovery period

(Lin, 2011). In this study, patients listened to a 10-minute audio tape via headphones twice a day,

PAIN CONTRACTS 5

at the same time each day, for three post-operative days. There were 93 total participants with 45

in the experimental group and 48 in the control group. The difference in severity of pain was

found to not be of statistical significance. However, via the ANOVA test, differences in systolic

blood pressure between the two groups was statistically significant (Lin, 2011). Although not all

results found statistical significance, pain was reduced in the patients who underwent relaxation

therapy.

“Non-pharmacological pain management can reduce the emotional effect of pain,

enhance adjustment and make patients believe they can control their pain, thus reducing pain and

promoting sleep” (Lin, 2011, p. 601). While many of the above non-pharmacological studies did

not find statistically significant evidence, all of them found some decrease in pain in the

experimental groups. Furthermore, in the present study, the pain contract is used as a method to

understand patient’s conceived idea of pain, along with what they consider manageable. The pain

contract is used as a simple, non-pharmacological measure to guide the healthcare providers and

aide in the proper interventions for pain control in the post-operative period.

Research Question

Does the implementation of a pain contract in total hip and knee arthroplasty patients

increase pain control in the post-operative period?

Methodology

Target Population

Participants in this study were from the orthopedic unit of St. Alexius Medical Center in

Hoffman Estates, Illinois. A census of 195 patients were included in the study. Inclusion criteria

consisted of being scheduled for a total joint arthroplasty, having surgery between May 2012 and

October 2012, and the ability to understand and verbalize pain according to the visual analog

PAIN CONTRACTS 6

scale (VAS) with faces. In most cases, a pain contract was initiated with those who attended the

pre-operative joint class. This allowed for random assignment to the control group (n=80) and

the experimental group (n=115), since patients had the option to attend the class or not. Patients

with a history of a previous total joint replacement surgery were excluded from the pre-operative

class, and were assigned to the control group.

Sampling Method

A census was used for this study as the overall population was quite small. In an effort to

avoid false results, the census was used to compensate for any cases that fell out. This means that

not all hip and knee total arthroplasty patients were included in the data set as not all patients had

completed audits at the four pain-audit check points in the post-operative period. At n=195,

power should easily reach the acceptable level at ≥ .80 because n>30. This means there is an

80% probability of achieving statistically significant results. Furthermore, for all tests run in this

study, α=0.05 was used for the error rate. This number was further derived using Bonferroni’s

correction. Bonferroni’s correction adjusts the p-value (α=0.05) when multiple statistical tests are

being run on the same data set (David Walker, personal communication, April 15, 2013).

Therefore, because five chi-square tests were run to answer the hypothesis, the p-value was

changed to α=0.01.

The dependent variable (DV) is pain control in the post-operative period while the

independent variable (IV) is the pain contract. The patient’s subjective assessment of pain on the

VAS scale is a potential intervening variable. For the sake of this study, it is assumed pain is a

subjective feeling to each individual patient and each patient correctly verbalized his/her pain at

the requested time.

PAIN CONTRACTS 7

Data Collection

Data was collected over a six-month span (May 2012-October 2012) on all total hip and

knee arthroplasty patients. Recorded data included: attendance at the pre-operative class, pain

contract initiation, the pain audit, and functional status (ability to ambulate 100 feet by

discharge). A pain audit was completed on each of these patients upon arrival to the unit, six

hours post-arrival to the unit, 24-hours post-arrival to the unit, and at the time of discharge. For

this study, pain control is defined as verbalizing pain as tolerable at all four checkpoints.

Tolerable pain is defined as pain rated at or below the numerical pain goal per the patient. The

pain goal in the control group was initiated upon arrival to the floor from recovery. The

experimental group set pain goals at the pre-operative class when filling out the pain contracts.

All variables in the study are nominal level data. Since pain is a subjective experience,

the use of nominal level data inhibited formulation of any grey areas. After reviewing all pain

audits, if pain was controlled at the specified time, then “yes” was recorded. If pain was not

controlled, then “no” was recorded. This also helped control any variables that could have

intervened with the study and cause extraneous results. Likewise, a pain contract was utilized or

it was not. It is noted that some patients are excluded from the pre-operative class (annotated as

‘3’) because they have had a previous total joint replacement surgery. However, these patients

still had the option of attending the class. Furthermore, any missing data was recorded as discrete

missing data, annotated as ‘999.’

Statistical Methods

Once coded, data were analyzed via the Statistical Package for Social Sciences (SPSS)

version 19.0 for Windows. As stated previously, an α of 0.01 after Bonferroni’s correction

adjustment was used for all statistical tests.

PAIN CONTRACTS 8

A chi-square test of independence was used to determine if there is an association

between pain contracts and post-operative pain in total hip and knee replacement patients. The

following assumptions are used in a chi-square test of independence:

1. At least 75% of the cells have expected frequencies ≥5 in any sized table. All cells in all

tables have expected frequencies ≥1 (David Walker, personal communication, April 8,

2013).

2. In a 2x2 table only, if <75% of the cells have expected frequencies <5, the Yates’

Continuity Correction is used. If only 1 out of the 4 cells has a count <5, the χ2 is

statistically significant and Yates’ is not, use the chi-square due to the conservative

natures of Yates (David Walker, personal communication, April 8, 2013).

3. If an observed count equals 0 or an expected frequency is <1 in a cell in a 2x2 table only,

an alternative χ2 is used, call Fisher’s Exact Test (David Walker, personal

communication, April 8, 2013).

Descriptive statistics including skewness, kurtosis, and standard deviation were not

measured to ensure normality of the data as they would be irrelevant due to the data’s nominal

level nature. Barcharts were analyzed to depict the data pictorially. A 2x2 contingency table was

used five times to answer the research question by running the chi-square test for independence.

Standard residuals were run to indicate any influential cells that may have driven statistical

significant results more than others. A standard residual finding >2 (positive or negative) defines

a specific cell contributing more to statistical significant results than other cells (David Walker,

personal communication, April 8, 2013).

PAIN CONTRACTS 9

The null hypothesis for the research question is that there is not an association between

pain contracts and post-operative pain. The alternative hypothesis is that there is an association

between pain contracts and post-operative pain.

Hₒ: χ2=0 χ2= ∑ (O-E)

2/E

H1: χ2≠0 df= (rows-1)(columns-1)

Analysis

Results

Five chi-square tests of independence were conducted to answer the proposed research

question: Does the implementation of a pain contract in total hip and knee arthroplasty patients

increase pain control in the post-operative period? The results from the chi-square tests are

depicted and explained below.

Figure 1

The first chi-square test (Figure 1) looked at pain upon arrival to the orthopedic floor

from the recovery room following surgery. The first assumption was met, since greater than 75%

PAIN CONTRACTS 10

of the cells had expected frequencies ≥5 and all cells in the table had expected frequencies ≥1.

Therefore, the chi-square test for independence was run. Statistical significance was not found as

the p-value = 0.112, which is not greater than α=0.01. After looking at the chi-square distribution

table, the critical value is 6.63 at the 0.01 level with 1 degree of freedom (Gravetter & Wallnau,

2011). Therefore, the sample value 2.527 is not beyond the critical value 6.63 and we fail to

reject the Hₒ that there is not an association between pain contracts and post-operative pain

control. The standardized residuals are not > 2 in any of the cells, which means there are no

particular cells that drove the findings more than others.

Figure 2

The second chi-square test (Figure 2) looked at pain six hours post-arrival to the floor

from recovery. The first assumption was again met as greater than 75% of the cells had expected

frequencies ≥5 and all cells in the table had expected frequencies ≥1. Therefore, the chi-square

test for independence was ran as the other assumptions were not met to run a different chi-square

test. Statistical significance was not found as the p-value = 0.196, which is not greater than

PAIN CONTRACTS 11

α=0.01. The critical value remains 6.63 at the 0.01 level with 1 degree of freedom. Therefore, the

sample value 1.670 is not beyond the critical value 6.63 and we fail to reject the Hₒ that there is

not an association between pain contracts and post-operative pain control. The standardized

residuals are not > 2 in any of the cells, which means no particular cells influenced the findings

more than others.

Figure 3

An alternative test, called Yates’ Continuity Correction was conducted for the third test

(Figure 3). This is because the second assumption was met. That is, less than 75% of the cells

have expected frequencies <5. More than 1 of the 4 cells have expected frequencies <5, so the

second part of the assumption does not pertain to the data in this instance. Statistical significance

was not found as p=0.623, which is not greater than α=0.01. The sample value=0.242 is not

greater than the critical value =6.63, and therefore we fail to reject the Hₒ that there is not an

association between pain contracts and post-operative pain control. Similar to the previous two

PAIN CONTRACTS 12

tests, none of the standardized residuals are >2. Thus, there are no particular cell drivers in this

instance either.

Figure 4

The fourth test (Figure 4) required running Fisher’s Exact Test after looking at the

assumptions. Two cells contained expected counts <1 and the table is 2x2, thus the alternative χ2

test, Fisher’s Exact Test, was used. The other assumptions did not apply to this situation. The p-

value =0.410, which is not greater than α=0.01. Therefore, we did not find statistical significance

and fail to reject the Hₒ that there is not an association between pain contracts and post-operative

pain control. Like the above four tests, none of the standardized residuals were >2 so, neither of

the cells were more influential than the others.

PAIN CONTRACTS 13

Figure 5

The final chi-square test (Figure 5) looked at pain control upon overall from arrival to the

floor after surgery to the time of discharge. The first assumption was met as greater than 75% of

the cells had expected frequencies ≥5 and all cells in the table had expected frequencies ≥1. The

other two assumptions did not apply to the data in this set. Therefore, the chi-square test for

independence was utilized. Statistical significance was not found as the p-value = 0.035, which is

not greater than α=0.01.The sample value 4.423 is not beyond the critical value 6.63 and we fail

to reject the Hₒ that there is not an association between pain contracts and post-operative pain

control. The standardized residuals are not > 2 in any of the cells, which delineates that none of

the cells contribute to the results more than the others.

None of the tests conducted reached statistical significance; therefore effect size was not

calculated.

PAIN CONTRACTS 14

Limitations

A limitation to this study is that it requires pain to be an objective finding when it is a

subjective experience. Therefore, it was assumed that nurses could correctly assess the patient’s

ability to adequately verbalize their pain when asked and relate it to their overall pain goal. If

members of the healthcare team correctly noted each patient’s pain goal and recorded their

specific pain level at the assessed times, there should be little room for error to occur. Nominal

level data, either “yes” or “no” answers, were used to help reduce the risk of variance in this

instance. There was also a difference in sample size between the control and experimental

groups. The experimental group was larger (n=115) than the control group (n=80), which

allowed the experimental group a greater opportunity to show a statistically significant difference

from the control group in regards to overall pain control in the post-operative period. Since the

chi-square test for independence was run five times, the Type I error rate may have inflated.

Bonferroni’s correction adjusted the overall p-value to decrease the instance of increased Type I

error. The chi-square test of independence does not show directionality, magnitude, or causality

of an association. This can be seen as a limitation at it cannot give any detail in regards to an

association between and independent and dependent variable.

Discussion, Conclusions, and Recommendations

Although statistical significance was not found in any of the chi-square tests for

independence, interesting and applicable information was produced. For instance, a post-hoc

point of interest was found. If the chi-square test for independence was only ran one time looking

at pain control overall in the post-operative period, α=0.05, and statistical significance would be

present. It is also interesting to look at each barchart depicted above in the results section. Pain is

PAIN CONTRACTS 15

controlled much more often than not judging by the substantially larger amount of green shown

in the barcharts.

Regardless of whether a pain contract is in place, pain is still controlled much more often

than it is not. It is interesting to note that 29% of patients without a pain contract could not

answer that their pain was controlled throughout the entire post-operative period at the four

checkpoints. Only 13% of patients with a pain contract in place did not have pain control at each

of the four pain audit times. This is a 16% difference, which is not statistically significant, but

should still be noted.

There are several clinical implications found from these findings. Overall, St. Alexius

Medical Center does well with pain control in the post-operative period for total hip and knee

arthroplasty patients. It would be beneficial to study the same data in surrounding area hospitals,

taking a sample from a larger population to run the chi-square test again. Perhaps, statistical

significance would be found. A longer research period may provide different results as well.

Moreover, pain control is an important variable to control in post-operative patients. Lack

of pain control decreases patient satisfaction, which decreases overall hospital scores and affects

reimbursement. Although the results were not found to be statistically significant, a substantial

increase (16%) in pain control was found with the use of a pain contract. This allows room for

improvement and might dictate a non-pharmacological measure that is worth investigating.

Implementation of pain contracts has shown some improvement in post-operative pain control.

More research needs to be conducted regarding their overall effect on post-operative pain

control.

PAIN CONTRACTS 16

References

Editorial. (2011). The role of the autonomic nervous system in acute surgical pain processing—

what do we know? Anaesthesia, 66, 539-549.

Gravetter, F., & Wallnau, L. (2011). Essentials of statistics for the behavioral sciences(7th

ed.).

Belmont, CA: Thompson Wadsworth.

Lin, P. (2011). An evaluation of the effectiveness of relaxation therapy for patients receiving

joint replacement surgery. Journal of Clinical Nursing, 21, 601-608. doi: 10.1111/j.1365-

2702.2010.03406.x

Murphy, S., Conway, C., McGrath, N., O’Leary, B., O’Sullivan, M., & O’Sullivan, D. (2011).

An intervention study exploring the effects of providing older adult hip fracture patients

with an information booklet in the early postoperative period. Journal of Clinical

Nursing, 20, 3404-3413. doi: 10.1111/j.1365-2702.2011.03784.x

Payne, R., Anderson, E., Arnold, R., Duensing, L., Gilson, A., Green, C., Haywood Jr., C.,

Passik, S., Rich, B., Robin, L., Shuler, N., & Christopher, M. (2010). A rose by another

name: pain contracts/agreements. The American Journal of Bioethics, 10(11), 5-12. doi:

10.1080/15265161.2010.519425

Vaajoki, A., Pietila, A., Kankkunen, P., & Vehvilainen-Julkunen, K. (2011). Effects of listening

to music on pain intensity and pain distress after surgery: an intervention. Journal of

Clinical Nursing, 21, 708-717. doi: 10.1111/j.1365-2702.2011.03829.x

Wong, C., Lin, L., Lee, H., & Liu, C. (2012). The analgesic effect of thermal therapy after total

knee arthroplasty. The Journal of Alternative and Complementary Medicine, 18(2), 175-

179. doi: 10.1089/acm.2010.0815