|MP 2.01.30||Biofeedback as a Treatment of Chronic Pain|
|Original Policy Date
|Last Review Status/Date
Reviewed with literature search/3:2014
|Return to Medical Policy Index|
Our medical policies are designed for informational purposes only and are not an authorization, or an explanation of benefits, or a contract. Receipt of benefits is subject to satisfaction of all terms and conditions of the coverage. Medical technology is constantly changing, and we reserve the right to review and update our policies periodically.
Biofeedback is a technique intended to teach patients self-regulation of certain physiologic processes not normally considered to be under voluntary control. Electromyography (EMG) biofeedback has been evaluated as a method to reduce chronic or recurrent pain of musculoskeletal or psychosomatic origin.
Treatment for chronic pain is often multimodal and typically includes psychologic therapy. Psychologic techniques vary but may include cognitive therapy, which teaches subjects the ability to cope with stressful stimuli by attempting to alter negative thought and dysfunctional attitudes, and behavioral approaches to reduce muscle tension and break the pain cycle. Relaxation, using any of a variety of techniques including meditation or mental imagery, is considered a behavioral therapy that may be used alone or as a component of a cognitive-behavioral therapy (CBT) program. EMG biofeedback has also been used for the treatment of chronic pain, with the assumption that the ability to reduce muscle tension will be improved through feedback of data to the subject regarding degree of muscle tension. While some consider EMG biofeedback to be a method to obtain relaxation, others consider biofeedback to be distinct from other relaxation procedures.
Biofeedback provides physiologic information not normally available to the patient, with a concerted effort on the part of the patient to use this feedback to help alter the physiologic process in some specific way. Biofeedback training is done either in individual or group sessions, alone, or in combination with other behavioral therapies designed to teach relaxation. A typical program consists of 10 to 20 training sessions of 30 minutes each. Training sessions are performed in a quiet, nonarousing environment. Subjects are instructed to use mental techniques to affect the physiologic variable monitored, and feedback is provided for successful alteration of that physiologic parameter. The feedback may be in the form of lights or tone, verbal praise, or other auditory or visual stimuli.
Biofeedback as a treatment of chronic pain, including but not limited to low back pain, is investigational.
No applicable information
BlueCard/National Account Issues
In many Plans, biofeedback is contractually excluded. If contractually excluded in the host Plan, but not in the home Plan, the host Plan may use this policy as the basis of coverage decisions for the home Plan.
Biofeedback may be offered as part of a comprehensive program in pain management as offered by pain management centers.
Psychologic treatments involve both nonspecific and specific therapeutic effects. Nonspecific effects, sometimes called placebo effects, occur as a result of therapist contact, positive expectancies on the part of the subject and the therapist, and other beneficial effects that occur as a result of being a patient in a therapeutic environment. Specific effects are those that occur only because of the active treatment, above any nonspecific effects that may be present. The literature review focuses on identifying evidence that biofeedback’s effects are not nonspecific placebo effects. Because an ideal placebo control is problematic with psychologic treatments and because treatment of chronic pain is typically multimodal, isolating the specific contribution of biofeedback is difficult. An ideal study design would be a randomized controlled trial (RCT) comparing biofeedback with a sham intervention; an alternative design would be an RCT comparing an intervention such as exercise with and without the addition of biofeedback.
This policy was originally based on a 1995 TEC Assessment, which concluded that evidence was insufficient to demonstrate the effectiveness of biofeedback for treatment of chronic pain.(1) The policy was updated regularly with searches of the MEDLINE database. The most recent literature search was performed for the period January 28, 2013, through January 23, 2014. Following is a summary of the key literature to date:
Several meta-analyses were identified that reviewed RCTs on psychologic therapies for a variety of nonheadache chronic pain conditions. A Cochrane review by Eccleston et al focused on chronic pain in adults; this systematic review was last updated in 2009.(2) Two RCTs were identified that compared behavioral therapy against an active control designed to change behavior (eg, exercise or instruction). Three RCTs had sufficient follow-up to be included in a comparison of behavioral therapy against usual treatment. The systematic review found that, although the quality of trial design had improved over time, there were too few studies to achieve a meaningful conclusion about the effects of behavioral therapy on pain, disability, or mood.
Another Cochrane review by Eccleston et al focused on children and adolescents with chronic and recurrent pain.(3) Although psychologic therapies were found to improve pain, only 1 of the 5 studies on nonheadache pain evaluated biofeedback. Biofeedback was not found to improve abdominal pain more than cognitive-behavioral therapy (CBT) in this trial (which was conducted by Humphreys and Gevirtz and is discussed in greater detail next, reference (4)). An updated meta-analysis of studies on psychologic therapies for management of chronic pain in children and adolescents was published by Palermo et al in 2010.(5) The review did not identify any new randomized trials on biofeedback for managing nonheadache pain.
RCTs and meta-analyses on biofeedback for specific chronic pain conditions
Low Back Pain
A 2010 Cochrane review on behavioral treatments for chronic low back pain included a meta-analysis of 3 small randomized trials comparing EMG biofeedback to a waiting-list control group.(6) In the pooled analysis, there were a total of 34 patients in the intervention group and 30 patients in the control group. The standard mean difference in short-term pain was -0.80 (95% confidence interval [CI], -1.32 to -0.28); this difference was statistically significant favoring the biofeedback group. The Cochrane review did not conduct meta-analyses of trials comparing biofeedback with sham biofeedback and therefore did not control for any nonspecific effects of treatment.
Two randomized trials have compared biofeedback with a sham intervention for treatment of lower back pain; neither found a statistically significant benefit with real biofeedback. Bush et al randomized 62 patients to either EMG biofeedback, sham biofeedback, or a no treatment control group for the treatment of lower back pain.(7) At the conclusion of the trial, all 3 groups showed significant improvement in multiple measures of pain. There were no significant effects found for treatment type, leading the authors to conclude that biofeedback is not superior to placebo in controlling chronic pain. More recently, in 2010, Kapitza et al compared the efficacy of respiratory biofeedback with sham biofeedback in 42 patients with lower back pain.(8) All participants were instructed to perform daily breathing exercises with a portable respiratory feedback machine; exercises were performed for 30 minutes on 15 consecutive days. Patients were randomized to an intervention group that received visual and auditory feedback of their breathing exercises or a control group that received a proxy signal imitating breathing biofeedback. Patients recorded pain levels in a diary 3 times a day, measuring pain on a visual analog scale (VAS). Both groups showed reduction in pain levels at the end of the intervention period and at the 3-month follow-up, but there were no significant differences in pain between groups. For example, the mean change in pain with activity 3 months after the intervention was a reduction in 1.12 points on a 10-point VAS scale in the intervention group and 0.96 points in the sham control group (p>0.05). The mean change in pain at rest after 3 months was a reduction of 0.79 points in the intervention group and 0.49 points in the control group (p>0.05).
Another randomized trial, by Glombiewski et al, assessed whether the addition of EMG biofeedback to CBT improved outcomes in 128 patients with lower back pain.(9) Patients with musculoskeletal pain of the low, mid, or upper back, with pain duration of at least 6 months on most days of the week, were randomized to CBT, CBT plus biofeedback, or a waiting-list control; 116 patients began the 1-hour weekly sessions (17-25 treatments) and were included in the final analysis. CBT alone included breathing exercises and progressive muscle relaxation; biofeedback was used for 40% of the CBT treatment time in the combined treatment condition. Both treatments were found to improve outcomes including pain intensity compared with a waiting-list control (moderate effect size of 0.66 for pain intensity in the CBT plus biofeedback group). However, the addition of biofeedback did not improve outcomes over CBT alone.
Chronic Knee Pain
In 2012, Collins et al published a systematic review and meta-analysis of RCTs on nonsurgical interventions for anterior knee pain.(10) In a pooled analysis of data from 2 trials, there was no significant benefit of adding EMG biofeedback to an exercise-only intervention at 8 to 12 weeks (standard mean difference [SMD], -22; 95% CI, -0.65 to 0.20).
Chronic Neck and Shoulder Pain
In 2011, Ma et al in Hong Kong published an RCT that included 72 patients with chronic (at least 3 months) computer work-related neck and shoulder pain.(11) Patients were randomized to 1 of 4 six-week interventions: Biofeedback, exercise, passive treatment (eg, hot packs), or a control group receiving only an educational pamphlet. Members of the biofeedback group were given a portable EMG biofeedback machine and were instructed to use it for 2 hours daily while performing computer work. The active exercise group was given an exercise routine to perform on their own for no longer than 20 minutes, 4 times a day. Sixty of 72 (83%) participants were available for the postintervention follow-up assessment (n=15 per group). At the end of the intervention, the average VAS score and Neck Disability Index (NDI) scores were significantly lower in the biofeedback group than in the other 3 groups. For example, the mean VAS postintervention was 1.87 (SD=0.74) in the biofeedback group and 2.10 (SD=1.34) in the active exercise group (p<0.05). Data were available on only 39 of 72 (54%) of participants at 6 months.
This study found a short-term benefit of a biofeedback intervention, but the magnitude of difference in the VAS scores and the NDI was small and of uncertain clinical significance. In addition, there were several methodologic limitations. The study was of small size and had a substantial number of dropouts. The interventions were not balanced in intensity, as the biofeedback intervention was more intensive (2 hours per day) than the other interventions, such as the passive treatment arm, which received two 15-minute sessions per week. Long-term data were not available due to the low follow-up rate, which at 6 months was too small for meaningful analysis.
A 2011 Cochrane review identified 17 trials evaluating nonpharmacologic psychologic interventions for adults with chronic orofacial pain, eg, temporomandibular joint (TMJ) disorder.(12) For the outcome short-term pain relief (≤3 months), there was a significantly greater reduction in pain with interventions that combined CBT and biofeedback compared with usual care (2 studies; SMD=0.46; 95% CI, 0.02 to 0.90). However, there was not a significant benefit of a combined CBT/biofeedback on longer-term ie, 6-month pain relief, and there were no studies that compared CBT alone with CBT combined with biofeedback. For biofeedback-only interventions, a pooled analysis of 2 studies on short-term pain relief did not find a significant benefit compared with usual care (SMD= -0.41; 95% CI, -1.06 to 0.25). There was only 1 study reporting long-term pain relief after a biofeedback-only intervention, so a pooled analysis could not be conducted. The authors concluded that there is weak evidence to support psychosocial interventions for managing chronic orofacial pain and the most promising evidence is for CBT, with or without biofeedback. They noted that the trials in the review were few in number and had a high risk of bias, and they recommended additional high-quality trials.
Conclusions of the Cochrane review are similar to previous systematic reviews on treatment of TMJ disorder.(13,14) They also concluded that there is weak evidence that psychosocial/physical therapy interventions, including biofeedback among others, are beneficial for treating TMJ but that there were few studies and they tended to be of poor methodologic quality.
In 2013, Glombiewski et al published a meta-analysis of studies on the efficacy of EMG and EEG biofeedback (ie, neurofeedback) for treating patients with fibromyalgia.(15) The authors identified 7 RCTs comparing biofeedback with a control condition in patients with fibromyalgia syndrome. Studies in which biofeedback was evaluated only as part of multicomponent interventions were excluded from the review. Three studies used EEG biofeedback and 4 used EMG biofeedback; there were a total of 321 patients. A sham intervention was used as a control condition in 4 studies, 2 using EEG biofeedback and 2 using EMG- biofeedback. In a pooled analysis of the studies using EMG biofeedback, biofeedback significantly reduced pain intensity compared with a comparison intervention (effect size, Hedges g, 0.86; 95% CI, 0.11 to 0.62). A pooled analysis of studies on EEG biofeedback did not find a significant benefit compared with control conditions. Pooled analyses of studies of EMG and EEG biofeedback did not find a significant benefit of the intervention on other outcomes including sleep problems, depression and health-related quality of life. None of the studies included in this review were high quality, with risk of bias assigned by the authors as either unclear or high for all included studies. In addition, all of the studies reported on short-term outcomes, resulting in a lack of evidence on whether longer-term outcomes are improved. (For more information on EEG-biofeedback, see Policy 2.01.28.)
Representative RCTs on EMG biofeedback include a trial by Buckelew et al, which was one of the larger trials, enrolling 119 patients with fibromyalgia, but which was not double-blinded.(16) Patients were randomly assigned to 1 of 4 treatment groups: (1) biofeedback/relaxation, (2) exercise training, (3) combination treatment, and (4) an educational/attention control program. While the combination treatment group had better tender point index scores than other treatment groups, this study did not address placebo effects or the impact of adding biofeedback to relaxation therapy. In another of the larger, unblinded RCTs, Van Santen et al included 143 women with fibromyalgia, and biofeedback combined with fitness training was compared with usual care.(17) The primary outcome evaluated was pain using a VAS. The authors reported no clear improvements in objective or subjective patient outcomes with biofeedback (or fitness training) over usual care. A small, double-blinded randomized trial from Asia compared actual and sham biofeedback on pain, fitness, function, and tender points in 30 patients with fibromyalgia.(18) Pain reduction as assessed on a VAS scale did not differ significantly between groups. The authors calculated that a sample size of 15 patients could detect a difference of 5 cm (10 cm max) on a VAS, suggesting that the study lacked adequate power.
Humphreys and Gevirtz(4) randomly assigned 64 patients to groups treated with increased dietary fiber; fiber and biofeedback; fiber, biofeedback, and CBT; or fiber, biofeedback, CBT, and parental support. The 3 multicomponent treatment groups were similar and had better pain reduction than the fiber-only group. This study does not address placebo effects. In a systematic review of recurrent abdominal pain therapies in children, Weydert et al concluded that behavioral interventions (CBT and biofeedback) have a general positive effect on nonspecific recurrent abdominal pain and are safe.(19) The specific effects of biofeedback were not isolated in this systematic review and cannot be assessed.
A 2012 meta-analysis of RCTs evaluating practitioner-based complementary and alternative medicine treatments (defined as any treatment not taken orally or applied topically) for osteoarthritis identified 2 trials on biofeedback.(20) One was an RCT with 40 patients that assessed whether the addition of biofeedback to strengthening exercises improved outcomes in patients with osteoarthritis.(21) After a 3-week treatment period, no significant differences between the 2 treatment conditions in pain or quality of life were found. The other RCT, published in 2007, compared electrical stimulation with biofeedback-assisted exercise in 50 women with knee osteoarthritis.(22) After 4 weeks of treatment, there were no statistically significant differences between groups in pain and functioning scores.
Systemic Lupus Erythematosus
In an RCT of 92 patients with systemic lupus erythematosus (SLE), Greco et al found patients treated with 6 sessions of biofeedback-assisted CBT for stress reduction had statistically significant greater improvements in pain posttreatment than a symptom-monitoring support group (p=0.044) and a usual care group (p=0.028).(23) However, these improvements in pain were not sustained at 9 months’ follow-up, and further studies are needed to determine the incremental benefits of biofeedback-assisted CBT over other interventions in patients with SLE.
A randomized study by Bergeron et al of 78 patients with vulvar vestibulitis compared biofeedback, surgery, and CBT.(24) Patients who underwent surgery had significantly better pain scores than patients who received biofeedback or CBT. No placebo treatment was used.
Ongoing clinical trials
A Study to Investigate the Effect of a New Postural Biofeedback Device on Low Back Pain (NCT01572779)(25): This trial randomized 96 patients with moderate or severe low back pain to wear a back strain monitor with and without the addition of biofeedback. The biofeedback intervention involves cues to prompt patients to alter their posture or position. Primary study outcomes are pain and disability scales. As of February 2014, this study is active but is not recruiting patients.
Biofeedback, defined as patient self-regulation of certain physiologic processes not normally considered to be under voluntary control, has been investigated for a variety of chronic pain conditions. Most of the published randomized controlled trials have not found a significantly greater benefit when biofeedback is offered instead of or in addition to other conservative interventions eg, exercise. In addition, the available RCTs tended to have small sample sizes, were limited by high dropout rates, and/or did not find that the benefits of biofeedback were sustained over time. Questions remain about the contribution of biofeedback beyond that of conservative treatments and about the specific effects of biofeedback beyond the nonspecific effects of similar sham interventions. The scientific evidence available at this time does not permit conclusions regarding the effect of this technology on health outcomes. Therefore, biofeedback for treating chronic pain is considered investigational.
Practice Guidelines and Position Statements
A 2011 guideline by the American College of Occupational and Environmental Medicine recommended biofeedback for “select patients with chronic low back pain as a component (not a separate procedure) of cognitive behavioral therapy (CBT) or as a procedure in the context of an interdisciplinary or functional rehabilitation program.” Biofeedback was not recommended for acute or subacute pack pain.(26)
A 2010 practice guideline by the American Society of Anesthesiologists Task Force on Chronic Pain Management and the American Society of Regional Anesthesia and Pain Medicine states that “cognitive behavioral therapy, biofeedback, or relaxation training: These interventions may be used as part of a multimodal strategy for patients with low back pain, as well as for other chronic pain conditions.”(27)
Medicare National Coverage
Biofeedback therapy is covered under Medicare only when it is reasonable and necessary for the individual patient for muscle re-education of specific muscle groups or for treating pathologic muscle abnormalities of spasticity, incapacitating muscle spasm, or weakness, and more conventional treatments (heat, cold, massage, exercise, support) have not been successful. This therapy is not covered for treatment of ordinary muscle tension states or for psychosomatic conditions.
- Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Biofeedback. TEC Assessments 1995; Volume 10:Tab 25.
- Eccleston C, Williams AC, Morley S. Psychological therapies for the management of chronic pain (excluding headache) in adults. Cochrane Database Syst Rev 2009; (2):CD007407.
- Eccleston C, Palermo TM, Williams AC et al. Psychological therapies for the management of chronic and recurrent pain in children and adolescents. Cochrane Database Syst Rev 2009; (2):CD003968.
- Humphreys PA, Gevirtz RN. Treatment of recurrent abdominal pain: components analysis of four treatment protocols. J Pediatr Gastroenterol Nutr 2000; 31(1):47-51.
- Palermo TM, Eccleston C, Lewandowski AS et al. Randomized controlled trials of psychological therapies for management of chronic pain in children and adolescents: an updated meta-analytic review. Pain 2010; 148(3):387-97.
- Henschke N OR, van Tulder MW et al. Behavioural treatment for chronic low-back pain. Cochrane Database Syst Reviews 2010; (7):CD002014. .
- Bush C, Ditto B, Feuerstein M. A controlled evaluation of paraspinal EMG biofeedback in the treatment of chronic low back pain. Health Psychol 1985; 4(4):307-21.
- Kapitza KP PT, Bernateck M et al. . First non-contingent respiratory biofeedback placebo versus contingent biofeedback in patients with chronic low back pain: A randomized double-blind trial. Appl Psychophysiol Biofeedback 2010; 35:207-17.
- Glombiewski JA, Hartwich-Tersek J, Rief W. Two psychological interventions are effective in severely disabled, chronic back pain patients: a randomised controlled trial. Int J Behav Med 2009; 17(2):97-107.
- Collins NJ, Bisset LM, Crossley KM et al. Efficacy of nonsurgical interventions for anterior knee pain: systematic review and meta-analysis of randomized trials. Sports Med 2012; 42(1):31-49.
- Ma C, Szeto GP, Yan T et al. Comparing biofeedback with active exercise and passive treatment for the management of work-related neck and shoulder pain: a randomized controlled trial. Arch Phys Med Rehabil 2011; 92(6):849-58.
- Aggarwal VR, Lovell K, Peters S et al. Psychosocial interventions for the management of chronic orofacial pain. Cochrane Database Syst Rev 2011; (11):CD008456.
- McNeely ML, Armijo Olivo S, Magee DJ. A systematic review of the effectiveness of physical therapy interventions for temporomandibular disorders. Phys Ther 2006; 86(5):710-25.
- Medlicott MS, Harris SR. A systematic review of the effectiveness of exercise, manual therapy, electrotherapy, relaxation training, and biofeedback in the management of temporomandibular disorder. Phys Ther 2006; 86(7):955-73.
- Glombiewski JA, Bernardy K, Hauser W. Efficacy of EMG- and EEG-Biofeedback in Fibromyalgia Syndrome: A Meta-Analysis and a Systematic Review of Randomized Controlled Trials. Evid Based Complement Alternat Med 2013; 2013:962741.
- Buckelew SP, Conway R, Parker J et al. Biofeedback/relaxation training and exercise interventions for fibromyalgia: a prospective trial. Arthritis Care Res 1998; 11(3):196-209.
- van Santen M, Bolwijn P, Verstappen F et al. A randomized clinical trial comparing fitness and biofeedback training versus basic treatment in patients with fibromyalgia. J Rheumatol 2002; 29(3):575-81.
- Babu AS, Mathew E, Danda D et al. Management of patients with fibromyalgia using biofeedback: a randomized control trial. Indian J Med Sci 2007; 61(8):455-61.
- Weydert JA, Ball TM, Davis MF. Systematic review of treatments for recurrent abdominal pain. Pediatrics 2003; 111(1):e1-11.
- Macfarlane GJ, Paudyal P, Doherty M et al. A systematic review of evidence for the effectiveness of practitioner-based complementary and alternative therapies in the management of rheumatic diseases: osteoarthritis. Rheumatology (Oxford) 2012; 51(12):2224-33.
- Yilmaz OO, Senocak O, Sahin E et al. Efficacy of EMG-biofeedback in knee osteoarthritis. Rheumatol Int 2010; 30:887-92.
- Durmus D, Alayli G, Canturk F. Effects of quadriceps electrical stimulation program on clinical parameters in the patients with knee osteoarthritis. Clin Rheumatol 2007; 26(5):674-8.
- Greco CM, Rudy TE, Manzi S. Effects of a stress-reduction program on psychological function, pain, and physical function of systemic lupus erythematosus patients: a randomized controlled trial. Arthritis Rheum 2004; 51(4):625-34.
- Bergeron S, Binik YM, Khalife S et al. A randomized comparison of group cognitive--behavioral therapy, surface electromyographic biofeedback, and vestibulectomy in the treatment of dyspareunia resulting from vulvar vestibulitis. Pain 2001; 91(3):297-306.
- Sponsored by Pro-Active Medical Pty Ltd. A Study to Investigate the Effect of a New Postural Bio-feedback Device on Low Back Pain (NCT01572779). Available online at: www.clinicaltrials.gov. Last accessed February, 2014.
- American College of Occupational and Environmental Medicine (ACOEM). Low back disorders,. 2011. Available online at: www.guideline.gov. Last accessed February, 2014.
- American Society of Anesthesiologists Task Force on Chronic Pain Management, American Society of Regional Anesthesia and Pain Medicine. Practice guidelines for chronic pain management: an updated report by the American Society of Anesthesiologists Task Force on Chronic Pain Management and the American Society of Regional Anesthesia and Pain Medicine. Available online at: www.guideline.gov. Last accessed February, 2014.
|CPT||90875–90876||Individual psychophysiological therapy incorporating biofeedback training by any modality (face-to-face with the patient), with psychotherapy (e.g., insight oriented, behavior modifying, or supportive psychotherapy); code range|
|90901||Biofeedback training by a modality|
|ICD-9 Procedure||94.39||Other individual psychotherapy (includes biofeedback)|
|ICD-9 Diagnosis||Investigational for all codes|
|HCPCS||E0746||Electromyography (EMG), biofeedback device|
|ICD-10-CM (effective 10/1/15)||Investigational for all codes|
|G56.40-G56.42||Causalgia of upper limb code range|
|G57.70-G57.72||Causalgia of lower limb code range|
|G89.0-G89.4||Pain, not elsewhere classified code range|
|G90.50-G90.59||Complex regional pain syndrome I code range|
|M25.50-M25.579||Pain in joint code range|
|M54.00-M54.9||Dorsalgia code range|
|M79.60-M79.676||Pain in limb, hand, foot, fingers and toes code range|
|ICD-10-PCS (effective 10/1/15)||ICD-10-PCS codes are only for use on inpatient services.|
|GZC9ZZZ||Mental health, none, other biofeedback|
|Type of Service||Medicine|
|Place of Service||Physician Office|
Biofeedback as a Treatment of Chronic Pain
Biofeedback, Chronic Pain
|04/01/98||Add to Medicine section||New policy|
|10/08/02||Replace policy||Policy updated; no change in policy statement|
|02/25/04||Replace policy||Policy updated with literature review; no change in policy statement|
|05/23/05||Replace policy||Literature review update for the period of 2004 through April 2005; reference No. 13 added. Policy statement unchanged|
|07/20/06||Replace policy||Literature review update for the period of April 2005 through May 2006; policy statement unchanged|
|09/18/07||Replace policy||Policy updated with literature review;references 14 and 15 added; no change in policy statement|
|11/13/08||Replace policy||Policy updated with literature review through August 2008; rationale revised and references reordered; reference number 8 added; policy statement unchanged|
|03/11/10||Replace policy||Policy updated with literature review through January 2010; references added and reordered; policy statement unchanged|
|3/10/11||Replace policy||Policy updated with literature review through January 2011. References 6, 7 and 9 added; other references renumbered. Policy statement unchanged|
|03/08/12||Replace policy||Policy updated with literature review through January 2012. References 10-12, 23 added; other references renumbered or removed. Policy statement unchanged.|
|03/14/13||Replace policy||Policy updated with literature review through February 2013. References 19, 21 and 24 added; other references renumbered or removed. Policy statement unchanged.|
|3/13/14||Replace policy||Policy updated with literature review through January 23, 2014. References 15 and 26 added; other references renumbered or removed. Policy statement unchanged.|