Pain Medication Use after Spine Surgery

Dear Editor: Spine surgery is one of the most difficult areas in which to achieve a good clinical outcome after surgery. When compared with the other orthopedic subspecialties, such as joint replacement surgery, a higher percentage of postoperative patients continue to have symptoms that require pain medication utilization and some require further surgeries. Failure rates associated with lumbar fusion surgeries range from 10% to 40% [1]. This high rate of unsuccessful spine surgery has generated the term “failed back surgery syndrome.” Strong indications for spine surgery are instability of the spine and neurological deficits including motor deficit and bladder and bowel dysfunction, while pain remains strictly a relative indication. However, an increasing number of spine surgeries are recently being performed based mainly on pain symptoms. The use of postoperative pain medication following spine surgery is nearly universal. However, despite the prevalence of use, there is no standardized protocol detailing the type, strength, or duration of pain medication use following specific procedures. Optimally, surgery should relieve the symptoms that brought the patient to surgery, with the termination of pain medication following the acute postoperative period, generally within 1 month. However, pain medication use is often continued long after this recovery period. The reason for pain medication implementation depends on individual circumstances; however, they are often needed for incomplete resolution of the symptoms for which surgery was originally indicated. In fact, previous literature described continuous pain medication use by a significant proportion of patients beyond 1 year after spine surgery. Ali et al. [2] reported that 35% of patients continued to take pain medications for symptoms at 38 months following fusion surgery for adult idiopathic scoliosis. In comparing lumbar disc arthroplasty with fusion for single-level degenerative disc disease, Blumenthal et al. [3] reported a narcotic use rate of 64% in the arthroplasty group and 80.4% in the lumbar fusion cohort at 24 months after surgery. Despite this high narcotic requirement, these patients were within a subgroup of patients that were categorized as a clinical success. Hallet et al. [4] reported that 64–83% of patients with lumbar single-level disc disease were taking at least one oral strong analgesic or anti-inflammatory agent at 2 years after decompression or fusion surgery. Among patients reported as achieving overall success following surgery for single-level lumbar degenerative disc disease at 24 months, Zigler et al. [5] reported that 31% of ProDisc patients and 39% of fusion patients remained on narcotics. While some patients may develop additional spine pathology 5–10 years after surgery, these conditions should not alter the 1–2-year outcomes after surgery. Thus, the surgery may not necessarily be as successful as the outcome measures would indicate in patients showing an improved visual analog scale (VAS) score or clinical outcome measures after surgery, who nevertheless continue to take strong pain medications. Indeed, some other pathologies of the spine might remain or the surgery may not have been indicated for the pathology diagnosed. In fact, Epstein and Hood [6] reported that 47 (17.2%) of 274 spinal consultations seen by a single neurosurgeon were scheduled for “unnecessary surgery.” The frequency of spinal surgery is increasing worldwide, accompanied by an increasing number of publications that describe the clinical outcomes. There are numerous reports of clinical outcome assessments following spine surgery in the literature, reporting a variety of clinical outcome measures. The most frequently used are the VAS score, Oswestry Disability Index, SF-36, Roland–Morris Questionnaire, Japanese Orthopaedic Association score, Scoliosis Research Society (SRS) Questionnaire, Odom score, Nurick scale, and neck disability index. However, most of these measures do not include an assessment of pain medication use. Some clinical outcome measures do incorporate such assessments, namely the SRS Questionnaire, Prolo scale, Stauffer–Coventry score, Robinson scale, and Beaujon score. Indeed, all of these measures have a separate component for pain medication use. In the SRS Questionnaire, pain medication use is a variable within the pain related section. In addition to the clinical outcome measures listed above, many clinical studies use the VAS score alone to assess pain. Thalgott et al. [7] reported that following circumferential anterior lumbar interbody fusion, the average back pain result for “with medication” was 3.21 (scale of 1–10) and for “without medication” was 5.58. Therefore, there was a 2.37 points difference in the score depending on medication use. Consequently, pain medication usage is a very important factor to consider when accurately assessing pain scores and clinical outcomes following spine surgery. Furthermore, preoperative, as well as postoperative pain medication usage may need to be considered in order to make a valid assessment of postoperative clinical outcomes and/or pain. The type, dosage, and frequency of pain medications also should be addressed. For example, narcotics usage likely affects the pain assessment more than nonsteroidal anti-inflammatory drug use. In conclusion, pain medication can affect clinical outcomes, and a detailed description of pain medication use is advocated when reporting clinical outcomes after spine surgery in the literature so that it can be better assessed; otherwise, the outcomes may be misleading. Future studies are expected to assess the effect of each pain medication relative to the VAS score, and modify the score accordingly. Alternatively, a new pain assessment measure may need to be devised that validly incorporates pain medication utilization.