Evaluating the Relationship Between Initial Injury, Referral to A Pain Clinic, and Medical Retirement from the Army: A Retrospective Analysis

ABSTRACT

Introduction

Soldiers are expected to deploy worldwide and must be medically ready in order to accomplish their mission. Soldiers unable to deploy for an extended period of time because of chronic pain or other conditions undergo an evaluation for medical retirement. A retrospective analysis of existing longitudinal data from an Interdisciplinary Pain Management Center (IPMC) was used to evaluate the temporal relationship between the time of initial duty restriction and referral for comprehensive pain care to being evaluated for medical retirement.

Methods

Patients were adults (>18 years old) and were cared for in an IPMC at least once between May 1, 2014 and February 28, 2018. A total of 1,764 patients were included in the final analysis. Logistic regression was used to evaluate the impact of duration between date of first duty restriction documentation and IPMC referral to the outcome variable of establishment of a permanent 3 (P3) profile.

Results

The duration between date of first duty restriction and IPMC referral showed a curvilinear relationship to probability of a P3 profile. According to our model, a longer duration before referral is associated with an increased probability of a subsequent P3 profile with the highest probability peaking at 19 months. The probability of P3 declines gradually for those who were referred later.

Discussion

This is the first time the relationship between time of initial duty restriction, referral to an IPMC, and subsequent P3 or higher profile has been tested. Future research is needed to examine medical conditions listed on the profile to see how they might contribute to the cause of referral to the IPMC.

Conclusion

A longer duration between initial duty restriction and referral to IPMC was associated with higher odds of subsequent P3 status for up to 19 months. Referral to an IPMC for comprehensive pain care early in the course of chronic pain conditions may reduce the likelihood of P3 profile and eventual medical retirement of soldiers.

INTRODUCTION

Soldiers are expected to deploy worldwide and must be medically ready to accomplish their mission. Soldiers unable to deploy for an extended period of time because of chronic pain or other condition(s) undergo an evaluation for medical retirement.

The duration between the initial duty restriction and referral to an Interdisciplinary Pain Management Center (IPMC) for management varies between patients. Most soldiers referred to the IPMC have been on work/duty restrictions at least once in their Army career. In the Army, those restrictions are recorded on a document called a “profile” that gives soldiers’ commanders instructions on which job-related activities each soldier can and cannot do. Profiling in the Army is outlined in Army Regulation 40-502.¹ The electronic version is called eProfile. An eProfile can be temporary or permanent and is graded in severity from a 1 (least severe) to 4 (most severe).¹ A temporary profile is written for an injury from which a full recovery is expected, whereas a permanent profile is used to denote work and physical training restrictions for an injury that is expected to be present for the remainder of the soldier’s career.¹ A permanent 3 (P3) profile typically requires evaluation for medical retirement by a Medical Evaluation Board (P3 status), whereas a permanent 2 (P2) allows the soldier to remain on duty with certain restrictions (P2 status).¹ Although multiple studies have reported factors leading to medical retirement across the services,^2–5 those studies did not specifically look at the time from initial duty restriction to medical retirement.

Time from initial duty restriction to referral to an interdisciplinary pain clinic may play a role in the chronicity of pain leading to P3 disability status. For example, Vora and colleagues studied low back pain in individuals referred to a multidisciplinary pain clinic and found a decrease in functional improvement as time since injury increased with little improvement occurring after 6 months.⁶ European studies have also investigated the issue of duration between pain onset or injury and initiating care at a specialty pain center. For example, a study conducted in Germany found that the mean duration between initial onset of pain and first appointment at a specialty pain center was 12 years.⁷ Another study conducted in Denmark found that patients on a waiting list for treatment of non-malignant chronic pain at a multidisciplinary pain clinic had been in pain for an average of 11.4 years (ranging from 6 months to 50 years).⁸ Finally, in a study conducted on U.S. workers’ compensation, participants demonstrated an initial time of injury to referral of 3 years.⁹ While these studies highlight a typically long duration between onset of pain or injury and referral or care at a specialty pain clinic, none of these studies evaluated the relationship between duration and return to work.

Medical disability is a continuum of health that is not always specific to an inciting injury. The World Health Organization’s International Classification of Functioning, Disability and Health (ICF) model of disability shows that a health condition should be considered within multiple domains to include the context of environmental and personal factors.¹⁰ According to Kostanjsek, “disability and functioning are, according to the ICF model, outcomes of interactions between health conditions (diseases, disorders and injuries) and contextual factors.”¹⁰ So the initial location of the injury may not be related to the reason for disability. Rather, time from any initial injury to being treated holistically for chronic pain at an IPMC may play a role in how much a person is disabled.

It is currently unknown if a relationship exists between the duration of time between initial duty restriction and referral to pain specialty care and its impact on medical retirement. To address this gap, we conducted a retrospective analysis of existing longitudinal data from an IPMC to evaluate the relationship between time since initial profile (TSIP) (with the TSIP defined as duration between initial duty restriction in the system and referral to an IPMC) and subsequent establishment of a P3 or P4 profile that would require a medical evaluation board evaluation.

METHODS

Institutional Review Board approval was obtained through Madigan Army Medical Center and data sharing agreements established between the Defense Health Agency Solution Delivery Division, University of Washington, and the Army in order to obtain the data and meet regulatory requirements. Inclusion and exclusion criteria are listed in Table I. All profiles in the eProfile system for the patients, not just the pain management profiles, were included for the evaluation. A total of 2,792 military personnel were referred to the IPMC at the study site during the study period, and all but 357 were Army soldiers. All eProfiles available in the system were requested for the patients in the cohort (i.e., patients could have more than one eProfile). After exclusions were applied, 1,764 patients remained and were included in the analysis (Fig. 1). Logistic regression was used to evaluate multiple independent variables with a nominal dependent variable. Stata 15.1 statistical software was used for the development of the model and figures. The outcome variable was presence of a P3 or P4 profile. The primary independent variable was TSIP.

TABLE I.

Table of Inclusion and Exclusion Criteria

Inclusion criteria: Adults (>18 years old); Cared for in MAMC IPMC; Completed at least one pain assessment between May 1, 2014 and February 28, 2018.

Exclusion criteria: Not in Army (Active Duty, Reserve or recently Retired); No profile before referral to IPMC; Only pregnancy profiles without other profiles; No permanent 2 profile or temporary profile within 5 years before referral to IPMC.

Abbreviations: IPMC, Interdisciplinary Pain Management Clinic; MAMC, Madigan Army Medical Center.

FIGURE 1.

Process for patient inclusion and selection of injury profile (IPMC = Interdisciplinary Pain Management Clinic, PUL = Physical capacity/stamina, Upper extremity condition, Lower extremity condition, HES = Hearing Eyes, Psychology (categories of eProfile).

RESULTS

A total of 1,764 patients were evaluated with 82.0% being male. A total of 18,037 profiles were evaluated with 81.8% of those being temporary profiles. The average number of profiles per soldier was 10.2 ± 6.9; (range 1-62). The median duration of profiles was 30 days (range 1-431, IQR = 41). Average duration between patients’ initial duty restriction in system and referral to the IPMC was 32.3 ± 17.0 months (range 0.13-60). There were 817 patients (46.3%) with at least one P2 established either before or after IPMC referral, and no patients with a P4 profile.

Controlling for gender and the presence of a P2 profile, we observed a significant curvilinear effect of TSIP on P3 status (Table II) with longer delay associated with an increasing probability of P3 until 19 months after which the probability decreases from 20 to 60 months TSIP. Fig. 2 shows this relationship. Probability of P3 profile increases from 20% to 27% from 1 to 19 months. Probability starts to decrease at month 20 and goes down to 26% at 2 years, to 22% at 3 years, to 14% at 4 years, and to 7% at 5 years.

TABLE II.

Multiple Logistic Regression Model Predicting P3 Disability Status. (TSIP before Establishment of P3 Profile)

Variables	Odds ratio (95% CI)	Standard error	z	P value
Male	1.21 (0.85-1.72)	0.22	1.06	0.29
P2 profile present	1.56 (1.19-2.06)	0.22	3.17	0.001
TSIP	1.04 (1.01-1.07)	0.17	2.31	0.02
TSIP2	0.999 (0.998-0.999)	0.0003	−3.69	<0.001
Constant	0.13 (0.08-0.23)	0.04	−7.33	n/a

Abbreviations: TSIP, time since initial profile; P3, permanent 3; P2, permanent 2; TSIP², square of TSIP.

FIGURE 2.

Predicted probability of Permanent Disability with 95% Confidence Interval across Time Since Initial Profile and Referral to Interdisciplinary Pain Management Clinic.

Note: Logistic regression model included sex and indicator permanent duty restriction, i.e.,P2, as convariates. Longer delay is associated with the increasing probability of a subsequent P3 up to 19 months, at 20 months the Probability decreases with longer delay.TSIP: Time since initial profile and referral to IPMC.IPMC: Interdisciplinary Pain Mangemanent Clinic.

DISCUSSION

We found that a longer duration between initial duty restriction and referral to the IPMC was associated with higher odds of a subsequent P3 profile up to 19 months. The presence of a P2 profile was associated with significantly increased odds of being issued a subsequent P3 profile. Within the ICF framework where disability is multifactorial, the time from any injury to the time the soldier is treated at an IPMC may lead to an increased risk of P3.

Limitations of this study should be noted. First, we did not have access to the medical justification for each profile, and therefore, we were not able to determine if the reason for the initial profile was a factor in being issued a P3 profile. Second, we did not have information on how long each patient had been assigned to the military base at the study site. It is acknowledged that changes in duty station may have led to delays in referral to the IPMC and to establishment of a P3 profile, because of the time required for medical providers to become familiar with patients who were new to their panel. Strengths of this study include the large number of patients evaluated (n = 1,764) as well as a well-defined study sample (i.e., patients were known Army patients of an IPMC).

This study revealed a few areas that need further evaluation and reflection. First, a target of opportunity to improve medical readiness is the 16% of patients who already had a P3 profile before being referred to the IPMC. Ideally, if soldiers with painful conditions do not respond to first-line therapies, they should promptly be referred for interdisciplinary pain care to decrease likelihood of referral to a medical retirement board. There appears to be a lot of variability in how referring providers view the purpose of an IPMC. Research that looks at opinions of providers would be helpful in evaluating that variability. Second, what is the reason that the probability of P3 increases up to 19 months and then begins to decrease? This is most likely multifactorial as per the ICF model and would be difficult to try to identify the multitude of reasons this might occur. Finally, the lack of a standardized nomenclature for the reason for profile makes it difficult to link with medical records in order to see what clinical factors might be involved for the restrictions on the profile. The eProfile is a separate readiness system and there is no link between the diagnosis of the provider visit in the electronic medical record and the reason for profile in the eProfile system. Future efforts need to be undertaken to make it easier to link the provider visit with the profile.

FUNDING

This research was supported in part by the National Institute of Nursing Research of the National Institutes of Health under award number #K24NR015340. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.