Return-to-duty Rates among Coalition Forces Treated in a Forward-deployed Pain Treatment Center: A Prospective Observational Study

Permission to conduct this study was granted by the Commander of Task Force 10 and all patients who consented to the procedures. An interventional pain clinic was established by two anesthesiologists at Ibn Sina Hospital in Baghdad, Iraq, between October 2005 and September 2006. Once established, data sets were developed for prospective data collection. Information regarding treatment capabilities was transmitted through military channels to units in Iraq. Battalion and brigade surgeons communicated predominantly through e-mail with the two pain practitioners to determine patient eligibility and treatment goals. Appropriate patients were transported to Ibn Sina, the only fixed US medical facility in country, primarily via  helicopters.

Patients were evaluated and treated on a “space available” basis because trauma management was the unit's primary mission. Patients were typically evacuated to the hospital helipad from a variety of outpatient clinics, and were treated either at the end of the operating room schedule or in between emergency cases, as circumstances permitted. After treatment, patients were sent to the pharmacy to pick up their prescriptions, and were housed in temporary barracks adjacent to the hospital. They generally returned to their units the next evening because it was safer to travel in darkness.

The decision to treat patients was based on the expectation that they were capable of and motivated to returning to full duty “in theater.” Only if the soldier, his or her commander, and the battalion surgeon all thought treatment was warranted was a consult submitted. Return-to-duty rates were based on serial correspondence with brigade surgeons, battalion surgeons, and unit commanders. The determination regarding a soldier's fitness to return to duty was usually made by the pain physician, although the brigade or battalion surgeon was the final arbiter of this judgment. Some of the key factors considered in this decision were the preliminary or anticipated success of the intervention, how essential the soldier was to his or her unit, what disposition the soldier wanted, and what the unit commander wanted. The criteria used to determine disposition were not fixed; rather, they were contingent on the soldier's military occupation specialty. For example, an infantry soldier might need to function at 80% of physical capacity to be deemed fit for duty, whereas the threshold for an administrative officer stationed in the “green zone” might be considerably less.

Diagnoses were based predominantly on history and physical examination, radiologic studies, and response to therapy. Computed tomography was coordinated ahead of time with primary care physicians at the Ibn Sina Outpatient Center, and obtained on all patients presenting with radiating lumbar or cervical pain. There was no magnetic resonance imaging capability or access to electromyography or nerve conduction studies. Treatment was generally multifaceted because the feasibility of soldiers returning for subsequent treatment was unpredictable. Because the primary goal was to conserve unit strength, patients often received several procedures during one treatment session.

Continuous variables are reported by mean and SD. Categorical demographic and clinical data are described using numbers of subjects and percentage. Because no statistical hypothesis was tested, no formal inferences are made.

In the 1-yr period the 10th CSH was deployed to Baghdad, Iraq, 132 patients were evaluated at the Ibn Sina Pain Clinic. The majority (86%) of these were coalition forces (fig. 1). Pain patients underwent a total of 209 procedures and required 69 follow-up visits (56 in US Army soldiers, 2 in a British soldier, 2 in an Australian soldier, 1 in a US contractor, and 8 in Iraqi nationals). The mean age was 33 yr (SD, 9.3 yr; range, 19–51 yr) for active duty personnel and 43 yr (SD, 8.8 yr; range, 12–55 yr) for government contractors and foreign nationals. There were 111 male patients and 21 female patients.

More than 90% of patients were treated for less than 48 h. Notable exceptions whereby patients were treated longer included 3 cases of severe, debilitating lumbosacral radiculopathy treated with an epidural steroid injection (ESI) followed by a continuous epidural local anesthetic infusion, 1 host nation civilian with complex regional pain syndrome who was treated with serial sympathetic blocks to facilitate physical therapy, and 7 patients with groin pain who were treated with intravenous opioids while awaiting medical evacuation to Germany. Although having adequate capabilities to treat casualties is of paramount importance in a system where levels (formerly known as echelons) of care are designed to allow for rapid transfer of stable patients, because bed capacity was generally less than 50%, space availability was never a limiting factor. The three most common indications for return visits were for repeat ESI, trigger point injections, and intraarticular facet blocks. Because there was no elective schedule at the pain clinic, these follow-up visits were coordinated on an as-needed basis with unit commanders and battalion surgeons.

The most common diagnosis was radiculopathy, which accounted for 63% (95% confidence interval, 54–72%) of all new consults. Most of these were secondary to a herniated disc (68%). Among the 71 patients who presented with radicular symptoms, most (89%) were lumbosacral radiculopathy. These cases were predominantly new onset (72%), although a significant minority experienced a recurrence or worsening of previous symptoms. Radicular pain was treated with transforaminal or interlaminar ESI, physical therapy, and pharmacotherapy (e.g. , nonsteroidal antiinflammatory drugs or adjuvants), usually in combination. In the 30 patients who received repeat ESI, the typical interval between injections was 2–4 weeks. Notable exceptions were the 3 patients (2 soldiers) hospitalized for continuous epidural infusions, who were reinjected with steroids before their catheters were pulled. Overall, 35% of coalition forces returned on separate occasions for a repeat injection. In response to this aggressive, multimodal treatment approach, no patient who presented with radicular pain was medically evacuated. In descending order, the next most common diagnoses were thoracic pain, groin pain, nonradicular leg pain, and axial low back pain (table 1).

ESI accounted for the bulk of the procedures (60%), most of which were lumbar transforaminal injections (81%). The second most frequent intervention performed was trigger point injections (n = 21), followed by lumbar intraarticular facet blocks, groin blocks, and corticosteroid injections for plantar fasciitis (table 2). Intraarticular facet injections were performed in lieu of medial branch blocks because of the lack of a radiofrequency generator to perform facet denervation.

Nonsteroidal antiinflammatory drugs were by far the most frequently used medication class, being prescribed to 70% of patients. Drugs used to treat neuropathic pain were administered to 10%, muscle relaxants were administered to 5%, and opioids were administered to 8% of patients. The most common use of opioids was to control severe pain during medical evacuation to a fourth level military treatment center (i.e. , to Landstuhl, Germany). Twenty-four percent of patients were referred to physical therapy, most of who presented with lumbar radiculopathy (table 3).

Resources were limited, but host nation civilians and Iraqi soldiers were treated as appointment slots became available. Among the 6 patients in this group, 4 presented with lumbar radicular symptoms, 1 with axial low back pain and 1 with complex regional pain syndrome. The patient with complex regional pain syndrome was a 12-yr-old boy with a blast injury from an improvised explosive device who underwent multiple interventions during his protracted hospital course.

Seven patients were medically evacuated out of Iraq secondary to chronic pain (1 US contractor and 6 US Army soldiers). All were males presenting with groin pain. Overall, the return-to-duty rate for coalition forces was 94.7%. For US forces who comprised the bulk of consults and procedural interventions, the return-to-unit rate was 94.6%. Among government contractors, 92.3% returned to work in country.

There are several key findings in this epidemiologic study, with the primary one being that prompt and aggressive pain management in a forward-deployed area can facilitate high return-to-duty rates. Injuries sustained by active duty soldiers may be more prevalent and qualitatively different than that observed in a civilian cohort. In a series of epidemiologic studies conducted in airborne, engineering, artillery, and light infantry units, injury prevalence rates have been reported to range between 66% and 95% per year.8–10Although there are no studies comparing injury rates in deployed and nondeployed military units, it is generally acknowledged that the incidence of treatable pain conditions is at least as high in theaters of combat, in part because of the nature of war and the relative lack of medical and social support systems.11These statistics underscore the growing need for pain management capabilities in forward-deployed areas.

With few exceptions, the diagnoses and treatment of patients treated in Iraq were similar to those of chronic pain patients medically evacuated to tertiary care military treatment facilities before the Ibn Sina Pain Clinic was established. There was a slightly higher incidence of certain inflammatory conditions such as plantar fasciitis, and more trigger point injections performed at Ibn Sina than in medically evacuated Operation Iraqi Freedom patients seen at fourth level treatment centers,4which may reflect the self-limiting nature of these conditions. Even without an accessible pain treatment center, many patients who presented with these “less debilitating” disorders would probably not have required medical evacuation but would have been less combat effective. Therapeutic interventions that could have been undertaken “in theater” in the absence of a pain management physician include pharmacotherapy and physical therapy; basic procedures such as trigger point injections, knee injections, plantar fascia injections, trochanteric bursa injections, and at CSH manned with anesthesia personnel, ESI, and groin blocks. From February through October 2004, a general medical officer battalion surgeon reported a greater than 95% return-to-duty rate in more than 100 soldiers with uncomplicated pain conditions treated with simple interventions (personal verbal communication from LT Kenneth Son, US Navy, Battalion Surgeon, 2nd Battalion, 4th Marines, Ramadi, Iraq, May 2007).

One difference between the medical treatment in the Ibn Sina CSH and a similar patient cohort in a fourth level medical treatment facility is that less opioids and adjuvants were administered (table 4).4Although patients on stable doses of opioids may be deployed pending medical clearance, military physicians are unlikely to initiate long-term treatment with opioids or other drugs with central nervous system side effects in a combat zone. But the most striking difference between our results and those reported previously by Cohen et al.  4is the stark contrast in return-to-duty rates (95% vs.  2%). There are several explanations for the improved return-to-duty rates found in this study, including strict selection criteria, early and aggressive treatment, the strong bonds that develop between deployed soldiers, and systematic problems with personnel logistics (i.e. , absence of a standard protocol by which treated soldiers can easily return to theater). First, only soldiers who were motivated to remain with their units were referred for pain treatment. If a commander did not want a soldier to remain with the unit, or a battalion surgeon thought the patient was a poor candidate for retention, the patient was not sent for treatment. Second, unlike at some academic pain clinics, diagnostic specificity was subordinated to treatment outcome, so that soldiers often received multiple interventions during the same treatment session. Third, medically evacuating a patient to the United States where he can rest and recuperate in relative comfort with his family may undermine a soldier's incentive to return to his unit. Fourth, the mechanisms and conditions under which a treated soldier can return to his unit are drastically different between third and fourth level treatment centers. All that was required for soldiers treated at Ibn Sina to return to their unit was a half-mile walk to the US Embassy helipad to await helicopter transport to their base of operations. But once a soldier ends up in a medical facility in the continental United States, there is no quick and easy path for them to return to combat. Finally, the return-to-duty rate in this study was likely inflated by the treatment of soldiers who would not have opted for medical evacuation even in the absence of forward-deployed pain management.

Comparing return-to-duty rates for other medical conditions treated in and outside theaters of combat reveals equivocal findings. For example, the return-to-duty rate when treating early combat stress symptoms with forward-deployed combat stress control units in Iraq is greater than 95%. Treating similar symptoms in CSH and Kuwait yields return-to-duty rates of approximately 70% and 50%, respectively. A soldier with signs of posttraumatic stress syndrome treated in Germany has only approximately a 10% chance to return to combat duty. If the soldier ends up receiving treatment in the United States for similar symptoms, he has virtually no chance of ever returning to duty in theater.‡

Whereas these findings support the early and aggressive treatment of acute medical conditions in theater, the treatment of renal colic in deployed soldiers portrays a different picture. Rozanski and Edmondson12reported that 92% of soldiers with kidney stones aggressively treated with primary care measures, cystoscopy, or stent placement at the 21st CSH in Mosul, Iraq, remained with their unit. Even when deployed soldiers required medical evacuation because of complicated stone disease, most returned to their units. Among 18 patients surgically treated for stone disease in Landstuhl, Germany, between December 2006 and May 2007, 15 returned to Iraq (personal written communication from CPT Michael McDonald, US Navy Medical Corps, Landstuhl, Germany, May 2007). The observation that return-to-unit rates for pain patients more closely reflect the experience of the Mental Health Advisory Team should not be surprising. In contrast to urolithiasis, which is typically characterized by a short and auspicious treatment course, the treatment of pain tends to be more prolonged and unpredictable, like combat stress. Recent studies conducted in both civilians and veterans have found a strong association between somatic symptoms, generalized anxiety, and other psychopathology.13,14 

The findings in this study may potentially impact how militaries prioritize resources. Because most militaries do not classify anesthesiologists by subspecialty training, operating an interventional pain treatment center downrange has become a serendipitous endeavor. Consequently, adequately treating soldiers with medical conditions such as radiculopathy sometimes necessitates evacuation to a tertiary care treatment facility, where the likelihood of them returning to their unit is significantly reduced. To maximize unit readiness, modern armies should consider shifting resources to ensure the availability of pain management capabilities in mature theaters of operation. Whether our high return-to-duty rate is a function of forward-deployed pain treatment, a carefully selected and highly motivated patient population, or a combination thereof is a question that needs to be answered.

In conclusion, the results of this epidemiologic study suggest that high return-to-duty rates are possible when early and aggressive pain management strategies are used in forward-deployed areas. Prospective studies with more sophisticated outcome measures are needed to identify which patients are most likely to benefit from early interventional pain treatment “in theater” and how best to implement this.

The authors thank MAJ Scott Griffith, M.D. (Pain Clinic Director, Walter Reed Army Medical Center, Washington, D.C.), and COL Paul Mongan, M.D. (Chief, Anesthesia and Operative Services, Walter Reed Army Medical Center), for their reviews of the manuscript.