Network Meta-analysis and Economic Evaluation of Neurostimulation Interventions for Chronic Nonsurgical Refractory Back Pain.

OBJECTIVES: Different types of spinal cord stimulation (SCS) have been evaluated for the management of chronic nonsurgical refractory back pain (NSRBP). A direct comparison between the different types of SCS or between closed-loop SCS with conventional medical management (CMM) for patients with NSRBP has not been previously conducted, and therefore, their relative effectiveness and cost-effectiveness remain unknown. The aim of this study was to perform a systematic review, network meta-analysis (NMA) and economic evaluation of closed-loop SCS compared with fixed-output SCS and CMM for patients with NSRBP. METHODS: Databases were searched to September 8, 2023. Randomized controlled trials of SCS for NSRBP were included. The results of the studies were combined using fixed-effect NMA models. A cost-utility analysis was performed from the perspective of the UK National Health Service with results reported as incremental cost per quality-adjusted life-year (QALY). RESULTS: Closed-loop SCS resulted in statistically and clinically significant reductions in pain intensity (mean difference [MD] 32.72 [95% CrI 15.69-49.78]) and improvements in secondary outcomes (Oswestry Disability Index [ODI] and health-related quality of life [HRQoL]) compared with fixed-output SCS at 6-month follow-up. Compared with CMM, both closed-loop and fixed-output SCS resulted in statistically and clinically significant reductions in pain intensity (closed-loop SCS vs. CMM MD 101.58 [95% CrI 83.73-119.48]; fixed-output SCS versus CMM MD 68.86 [95% CrI 63.43-74.31]) and improvements in secondary outcomes (ODI and HRQoL). Cost-utility analysis showed that closed-loop SCS dominates fixed-output SCS and CMM, and fixed-output SCS also dominates CMM. DISCUSSION: Current evidence showed that closed-loop and fixed-output SCS provide more benefits and cost-savings compared with CMM for patients with NSRBP.

Cost-utility Analysis of Evoke Closed-loop Spinal Cord Stimulation for Chronic Back and Leg Pain.

OBJECTIVES: The effectiveness of Evoke closed-loop spinal cord stimulation (CL-SCS), a novel modality of neurostimulation, has been demonstrated in a randomized controlled trial (RCT). The objective of this cost-utility analysis was to develop a de novo economic model to estimate the cost-effectiveness of Evoke CL-SCS when compared with open-loop SCS (OL-SCS) for the management of chronic back and leg pain. METHODS: A decision tree followed by a Markov model was used to estimate the costs and outcomes of Evoke CL-SCS versus OL-SCS over a 15-year time horizon from the UK National Health Service perspective. A "high-responder" health state was included to reflect improved levels of SCS pain reduction recently reported. Results are expressed as incremental cost per quality-adjusted life year (QALY). Deterministic and probabilistic sensitivity analysis (PSA) was conducted to assess uncertainty in the model inputs. RESULTS: Evoke CL-SCS was estimated to be the dominant treatment strategy at ~5 years postimplant (ie, it generates more QALYs while cost saving compared with OL-SCS). Probabilistic sensitivity analysis showed that Evoke CL-SCS has a 92% likelihood of being cost-effective at a willingness to pay threshold of £20,000/QALY. Results were robust across a wide range of scenario and sensitivity analyses. DISCUSSION: The results indicate a strong economic case for the use of Evoke CL-SCS in the management of chronic back and leg pain with or without prior spinal surgery with dominance observed at ~5 years.

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation.

BACKGROUND: Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity. AIM: The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response". DISCUSSION: Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

Screening trials of spinal cord stimulation for neuropathic pain in England-A budget impact analysis.

Screening trials of spinal cord stimulation (SCS) prior to full implantation of a device are recommended by expert guidelines and international regulators. The current study sought to estimate the budget impact of a screening trial of SCS and the costs or savings of discontinuing the use of a screening trial. A budget impact analysis was performed considering a study population that reflects the size and characteristics of a patient population with neuropathic pain in England eligible for SCS. The perspective adopted was that of the NHS with a 5-year time horizon. The base case analysis indicate that a no screening trial strategy would result in cost-savings to the NHS England of £400,000-£500,000 per year. Sensitivity analyses were conducted to evaluate different scenarios. If ≥5% of the eligible neuropathic pain population received a SCS device, cost-savings would be >£2.5 million/year. In contrast, at the lowest assumed cost of a screening trial (£1,950/patient), a screening trial prior to SCS implantation would be cost-saving. The proportion of patients having an unsuccessful screening trial would have to be ≥14.4% for current practice of a screening trial to be cost-saving. The findings from this budget impact analysis support the results of a recent UK multicenter randomized controlled trial (TRIAL-STIM) of a policy for the discontinuation of compulsory SCS screening trials, namely that such a policy would result in considerable cost-savings to healthcare systems.

A risk-adjusted and anatomically stratified cohort comparison study of open surgery, endovascular techniques and medical management for juxtarenal aortic aneurysms-the UK COMPlex AneurySm Study (UK-COMPASS): a study protocol.

INTRODUCTION: In one-third of all abdominal aortic aneurysms (AAAs), the aneurysm neck is short (juxtarenal) or shows other adverse anatomical features rendering operations more complex, hazardous and expensive. Surgical options include open surgical repair and endovascular aneurysm repair (EVAR) techniques including fenestrated EVAR, EVAR with adjuncts (chimneys/endoanchors) and off-label standard EVAR. The aim of the UK COMPlex AneurySm Study (UK-COMPASS) is to answer the research question identified by the National Institute for Health Research Health Technology Assessment (NIHR HTA) Programme: 'What is the clinical and cost-effectiveness of strategies for the management of juxtarenal AAA, including fenestrated endovascular repair?' METHODS AND ANALYSIS: UK-COMPASS is a cohort study comparing clinical and cost-effectiveness of different strategies used to manage complex AAAs with stratification of physiological fitness and anatomical complexity, with statistical correction for baseline risk and indication biases. There are two data streams. First, a stream of routinely collected data from Hospital Episode Statistics and National Vascular Registry (NVR). Preoperative CT scans of all patients who underwent elective AAA repair in England between 1 November 2017 and 31 October 2019 are subjected to Corelab analysis to accurately identify and include every complex aneurysm treated. Second, a site-reported data stream regarding quality of life and treatment costs from prospectively recruited patients across England. Site recruitment also includes patients with complex aneurysms larger than 55 mm diameter in whom an operation is deferred (medical management). The primary outcome measure is perioperative all-cause mortality. Follow-up will be to a median of 5 years. ETHICS AND DISSEMINATION: The study has received full regulatory approvals from a Research Ethics Committee, the Confidentiality Advisory Group and the Health Research Authority. Data sharing agreements are in place with National Health Service Digital and the NVR. Dissemination will be via NIHR HTA reporting, peer-reviewed journals and conferences. TRIAL REGISTRATION NUMBER: ISRCTN85731188.

The Unmet Need for Intrathecal Drug Delivery Pumps for the Treatment of Cancer Pain in England: An Assessment of the Hospital Episode Statistics Database.

OBJECTIVES: Intrathecal drug delivery (ITDD) devices have been shown to be a clinically effective and cost-effective option for the management of cancer pain and recommended for use in England. The aim of this study is to assess the impact of the 2015 NHS England Clinical Commissioning Policy on the uptake of ITDD pumps for the management of cancer pain or if there is an ongoing unmet need for this intervention in England. MATERIALS AND METHODS: Hospital Episode Statistics (HES) were obtained for all patients undergoing ITDD for the management of cancer pain between 2014 and January 2020. In addition, HES were utilized to estimate the number of patients with cancer potentially eligible for ITDD pump during the same period. RESULTS: The number of patients with cancer and those potentially suitable to receive an ITDD for the management of cancer pain have increased year on year since 2014. This increase has not been matched by an uptake in the provision of ITDD. Conservative estimates suggest that at least 8000 people with cancer pain would be eligible for ITDD; 458 patients received an intervention for pain management between April 2018 and March 2019 and only 30 ITDD pumps were implanted in that same period. CONCLUSIONS: We observed a substantial gap between the need and provision of ITDD for patients with refractory cancer pain in England despite the recommendation for the use of ITDD for this patient population. In addition, we present suggestions for improvement of access to and provision of ITDD in England.

Does a screening trial for spinal cord stimulation in patients with chronic pain of neuropathic origin have clinical utility and cost-effectiveness (TRIAL-STIM)? A randomised controlled trial.

Spinal cord stimulation (SCS) is an established treatment of chronic neuropathic pain. Although a temporary SCS screening trial is widely used to determine whether a patient should receive permanent SCS implant, its evidence base is limited. We aimed to establish the clinical utility, diagnostic accuracy, and cost-effectiveness of an SCS screening trial. A multicentre single-blind, parallel two-group randomised controlled superiority trial was undertaken at 3 centres in the United Kingdom. Patients were randomised 1:1 to either SCS screening trial strategy (TG) or no trial screening strategy (NTG). Treatment was open label, but outcome assessors were masked. The primary outcome measure was numerical rating scale (NRS) pain at 6-month follow-up. Between June 2017 and September 2018, 105 participants were enrolled and randomised (TG = 54, NTG = 51). Mean numerical rating scale pain decreased from 7.47 at baseline (before SCS implantation) to 4.28 at 6 months in TG and from 7.54 to 4.49 in NTG (mean group difference: 0.2, 95% confidence interval [CI]: -1.2 to 0.9, P = 0.89). We found no difference between TG and NTG in the proportion of pain responders or other secondary outcomes. Spinal cord stimulation screening trial had a sensitivity of 100% (95% CI: 78-100) and specificity of 8% (95% CI: 1-25). The mean incremental cost-effectiveness ratio of TG vs NTG was £78,895 per additional quality-adjusted life-year gained. In conclusion, although the SCS screening trial may have some diagnostic utility, there was no evidence that an SCS screening TG provides superior patient outcomes or is cost-effective compared to a no trial screening approach.

A Systematic Review of Economic Evaluations Reporting the Cost-Effectiveness of Spinal Cord Stimulation.

OBJECTIVES: Spinal cord stimulation (SCS) is a recognized treatment for chronic pain. This systematic review aims to assess economic evaluations of SCS for the management of all chronic pain conditions, summarize key findings, and assess the quality of studies to inform healthcare resource allocation decisions and future research. METHODS: Economic evaluations were identified by searching general medical and economic databases complemented with screening of reference lists of identified studies. No restrictions on language or treatment comparators were applied. Relevant data were extracted. The quality of included studies was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. RESULTS: Fourteen studies met the inclusion criteria and were judged to be of acceptable quality. Economic evaluations assessed SCS for the management of refractory angina pectoris, failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), diabetic peripheral neuropathy (DPN), and peripheral arterial disease. Model-based studies typically applied a 2-stage model, i.e. decision tree followed by Markov model. Time horizon varied from 1 year to lifetime. Cost-effectiveness ranged widely from dominant (SCS cost-saving and more effective) to incremental cost-effectiveness ratio of >£100,000 per quality-adjusted life-year. Cost-effectiveness appeared to depend on the time horizon, choice of comparator, and indication. Ten of the studies indicated SCS as cost-saving or cost-effective compared with the alternative strategies. CONCLUSION: The results consistently suggest that SCS is cost-effective when considering a long-term time horizon, particularly for the management of FBSS and CRPS. Further studies are needed to assess the cost-effectiveness of SCS for ischemic pain and DPN.

Trial Versus No Trial of Spinal Cord Stimulation for Chronic Neuropathic Pain: Cost Analysis in United Kingdom National Health Service.

OBJECTIVES: The aim of the current project was to evaluate the spinal cord stimulation (SCS) screening trial success rate threshold to obtain the same cost impact across two identical sets of patients following either a prolonged screening trial prior to implantation strategy or a full implant without a screening trial. MATERIALS AND METHODS: A cost impact analysis was carried out from a health care perspective and considered trial to implant rates reported in the literature. Items of resource use were costed using national averages obtained from the National Health Service (NHS) reference cost data base. Cost components were added up to derive total patient level costs for the NHS. Only the costs associated with the screening trial procedures and devices were considered. RESULTS: The most conservative of our estimates suggest that a failure rate of less than 15% is cost saving to the NHS. A failure rate as high as 45% can also be cost saving if the less expensive nonrechargeable SCS devices are used. All the thresholds observed represent a considerably higher screening failure rate than that reported in the latest randomized controlled trials (RCTs) of SCS. A trial to implant ratio of 91.6% could represent savings between £16,715 (upper bound 95% CI of rechargeable implantable pulse generator [IPG] cost) and £246,661 (lower bound 95% CI of nonrechargeable IPG cost) per each 100 patients by adopting an implantation only strategy. CONCLUSIONS: Considerable savings could be obtained by adopting an implantation strategy without a screening trial. It is plausible that accounting for other factors, such as complications that can occur with a screening trial, additional savings could be achieved by choosing a straight to implant treatment strategy. Nevertheless, additional evidence is warranted to support this claim.

Intrathecal Drug Delivery Systems for the Management of Chronic Noncancer Pain: A Systematic Review of Economic Evaluations.

BACKGROUND: Intrathecal drug delivery (ITDD) systems are one of a limited number of management options for chronic noncancer pain, cancer pain, and spasticity. Concerns over their effectiveness and high initial costs led National Health Service (NHS) England to decommission ITDD for patients with chronic noncancer pain. However, the extent to which this decision is in line with existing economic evidence is unclear. The aim of this systematic review was to identify and review the existing evidence on the cost effectiveness of ITDD for chronic noncancer pain. METHODS: Full and partial economic evaluations on ITDD were identified through systematic searches in MEDLINE, Embase, Web of Science, and the NHS for Reviews and Dissemination databases. Database searches were complemented by hand searching of reference lists of relevant studies and searches of grey literature. Study selection was carried out by 2 assessors, independently. Study quality assessment was performed to inform critical appraisal of health economics studies. Data were extracted using a data extraction form developed for the purposes of this study. RESULTS: Four thousand four hundred and sixty-four unique studies were identified, of which 7 met the inclusion criteria. With the exception of 1 study, the studies found ITDD to be either cost saving or cost effective compared to conventional medical management. ITDD became cost ineffective in 1 further study following price year adjustment to 2016. CONCLUSIONS: Study findings showed ITDD to be not cost effective only in extremely conservative scenarios. There is limited evidence on the effectiveness of ITDD in noncancer pain; however, the available economic evidence controverts arguments to refute the treatment on economic grounds.

Decision analytic model of the diagnostic pathways for patients with suspected non-alcoholic fatty liver disease using non-invasive transient elastography and multiparametric magnetic resonance imaging.

OBJECTIVES: The mortality associated with liver disease continues to increase, despite the improvements implemented in the UK healthcare as does the prevalence of non-alcoholic fatty liver disease (NAFLD), given the escalating prevalence of obesity. The currently available methods to assess and monitor the stage of liver disease present several limitations. Recently, multiparametric MRI has been developed to address these limitations. The aim of this study is to develop a decision analytic model for patients with suspected NAFLD, to investigate the effect of adding multiparametric MRI to the diagnostic pathway. PERSPECTIVE: The model takes the perspective of the UK National Health Service (NHS) as the service provider. METHODS: A simple decision-tree model was developed to compare the costs associated with 3 diagnostic pathways for NAFLD that use non-invasive techniques. First, using transient elastography alone; second, using multiparametric MRI as an adjunct to transient elastography and third, multiparametric MRI alone. The model was built to capture these clinical pathways, and used to compare the expected diagnostic outcomes and costs associated with each. RESULTS: The use of multiparametric MRI as an adjunct to transient elastography, while increasing screening costs, is predicted to reduce the number of liver biopsies required by about 66%. Used as the sole diagnostic scan, there remains an expected 16% reduction in the number of biopsies required. There is a small drop in the overall diagnostic accuracy, as in the current model, liver biopsy is presumed to give a definitive diagnosis. CONCLUSIONS: The inclusion of multiparametric MRI, either as an adjunct to or replacement of transient elastography, in the diagnostic pathway of NAFLD may lead to cost savings for the NHS if the model presumptions hold. Further high-quality clinical evidence and cost data are required to test the model's predictions.

Intrathecal drug delivery systems for the management of chronic non-cancer pain: protocol for a systematic review of economic evaluations.

INTRODUCTION: Intrathecal drug delivery (ITDD) systems are an option for the management of patients with chronic non-cancer pain, cancer pain and spasticity. Concerns over their invasiveness and high initial costs have led National Health Service (NHS) England to decommission ITDD for patients with chronic non-cancer pain. However, the extent to which this decision is in line with existing economic evidence is unclear. To address this question, we will carry out a systematic review to identify and evaluate the existing evidence on the cost-effectiveness of ITDD for chronic non-cancer pain. METHODS AND ANALYSIS: A high-sensitivity search strategy will be employed in Cochrane Library, MEDLINE, EMBASE, Web of Science, NHS EED, DARE and HTA. Database searches will be complemented by additional searching techniques. Screening of the results will be performed by 2 reviewers independently using predetermined inclusion and exclusion criteria. Full and partial economic evaluations will be included. Data extraction will be carried out using a form created for the purposes of this review. Quality assessment of all included studies will be performed using recommended checklists. ETHICS AND DISSEMINATION: Ethical approval is not required as primary data will not be collected. Findings will be disseminated through peer-reviewed publications and conference presentations. PROSPERO REGISTRATION NUMBER: CRD42016035266.

The need for and provision of intrathecal baclofen therapy for the management of spasticity in England: an assessment of the Hospital Episode Statistics database.

OBJECTIVES: The aim of this study was to evaluate changes in the uptake of intrathecal baclofen (ITB) following commissioning of this therapy by the National Health Service (NHS) England in April 2013. The specific objectives of this study were: (i) to explore the gap between the need for and the actual provision of ITB services; and (ii) to compare England figures with other European countries with comparable data available. SETTING: Data for ITB -related procedures were obtained from the Hospital Episode Statistics (HES) database from 2009/2010 to 2013/2014. PARTICIPANTS: Patients receiving ITB for the management of spasticity. RESULTS: The available data for implantation of ITB from 2009/2010 to 2013/2014 for the treatment of spasticity due to varied aetiologies show that there has not been an increase in uptake of this therapy. The estimated need for this treatment based on the incidence and prevalence of conditions susceptible to ITB therapy is between 4.6 and 5.7 per million population. Our analysis of the data available from the HES database showed that the actual number of implants is around 3.0 per million population. The same period 2009-2014 has seen an increase in the delivery of other neuromodulation techniques including spinal cord stimulation, deep brain stimulation and sacral nerve stimulation. CONCLUSIONS: There is a considerable gap between the need for and provision of ITB figures nationally. Additionally, within the same area, we have observed important differences in the ITB service delivery between the various trusts. The reasons for this can be multifactorial, including individual experience and opinions, organisational structures, resource and financial limitations. Further research analysing the efficacy and cost-effectiveness of this treatment in the UK might inform the development of Technology Appraisal Guidance for ITB, potentially leading to an improvement in service provision.

Analysis of psychological characteristics impacting spinal cord stimulation treatment outcomes: a prospective assessment.

BACKGROUND: Psychological factors are recognised as influencing the outcome of spinal cord stimulation (SCS) although there is currently no consensus as to which factors impact upon SCS efficacy. OBJECTIVE: To identify psychological characteristics that may impact the efficacy of SCS. STUDY DESIGN: Prospective evaluation. SETTING: Single secondary care center in Dudley, United Kingdom. PATIENTS: Seventy-five patients were initially recruited and 56 patients (31 women and 25 men) were followed-up for 12-months. INTERVENTION: SCS for the management of chronic non-cancer pain. MAIN OUTCOME MEASURES: Outcome measures assessed at baseline, 6 months, and 12 months following SCS implantation included the visual analogue scale (VAS), Oswestry disability index (ODI), hospital anxiety and depression (HAD) scale, and the pain coping strategies questionnaire (PCSQ). RESULTS: Statistically significant improvements were observed for the VAS (P < 0.001), ODI (P = 0.011), anxiety (P = 0.042), and depression (P = 0.010) in the HAD scale and for the subscales reinterpreting pain sensation (P = 0.018), control over pain (P = 0.001), and ability to decrease pain (P < 0.001) of the PCSQ. We observed that depression and autonomous coping (control over pain, ability to reduce pain, and catastrophizing) may impact sensory aspects such as pain intensity and disability scores affecting the outcome of SCS treatment. Age at time of implant and duration of pain prior to implant were also found to impact SCS efficacy. LIMITATIONS: It has been reported that loss of analgesia may be experienced within 12 to 24 months following SCS implantation and therefore, it would be of interest to follow patients over a longer period. CONCLUSIONS: This study demonstrates that psychological aspects such as depression and autonomous coping may impact SCS treatment. Addressing these issues prior to SCS implantation may improve SCS long-term outcome.

Prevalence and influence of diagnostic criteria in the assessment of hypogonadism in intrathecal opioid therapy patients.

BACKGROUND: Hypogonadism is frequently diagnosed based on total testosterone (TT) levels alone. However, 99% of testosterone is bound to the sex hormone-binding globulin (SHBG) with only 1% free testosterone. Alternative assessment methods consist of assay of free testosterone (FT) or bioavailable testosterone (BT) by equilibrium dialysis, calculation of FT and BT through the Vermeulen equations, and calculation of the free androgen index (FAI). OBJECTIVES: The aim of this study was to investigate the prevalence of hypogonadism in male chronic non-cancer pain patients undertaking long-term intrathecal opioid therapy and the existence of diagnostic discrepancies according to the criteria used. STUDY DESIGN: Prospective observational study. SETTING: Department of Pain Management, Russells Hall Hospital, Dudley, United Kingdom. METHODS: Twenty consecutive male patients undertaking long-term intrathecal opioid therapy had the gonadal axis evaluated by assays of luteinising hormone (LH), follicle stimulating hormone (FSH), TT, SHBG and by calculating the FT, BT and FAI. RESULTS: Hypogonadism was present in 17 (85%) of the patients based on TT; 17 (85%) according to FT and BT calculations; and 14 (70%) when calculating FAI. Based on either TT or FT being low or borderline/low, 19 (95%) of the investigated patients were biochemically hypogonadal. Significant differences were observed between diagnosis based on FT and FAI (P < 0.05). No significant differences were observed between diagnosis based on TT and FT (P = 0.40) or TT and FAI (P = 0.20). CONCLUSION: Hypogonadism is common in patients undertaking intrathecal opioid therapy for the management of chronic non-malignant pain; however, diagnostic criteria can influence the diagnosis of this side effect. The assessment of the hypothalamic-pituitary-gonadal axis should include evaluation of total serum testosterone, free testosterone, or bioavailable testosterone.

Influence of a latent period in QALY analysis: pilot study of intrathecal drug delivery systems for chronic non-malignant pain.

Cost effectiveness of a treatment is an important factor in decision making in the United Kingdom. Preceding most interventional health care treatments there is a waiting period between decision and procedure where health care costs may be lessened. Intrathecal drug delivery systems (IDDS) are a recognised pain management therapy for chronic non-malignant pain. To our knowledge, the period of time between being placed on a waiting list for IDDS and the implant (latent period) has not been taken into consideration for cost effectiveness analysis. A retrospective longitudinal analysis of all pain related costs for a period no less than 4 years was undertaken by assessment of medical records of 12 consecutive patients implanted with IDDS for chronic non-malignant pain. The total cost of patient care for 2 years before latent, the latent period itself and 2 years after the implant of an IDDS was computed, according to the National Health Service tariff. An EQ-5D questionnaire was filled by all participants before and after IDDS implant. Total costs were converted to cost per day for comparison with latent period. The average duration of the latent period was 263 ± 176 days (range 3-489). The cost of conventional treatments during the pre-implant phase excluding the latent period was significantly higher (M = £ 5,005.86, SE = £ 918.56) compared with the costs of the same phase including the latent period (M = £ 4,086.35, SE = £ 959.09, t(11) = 2.23, p = 0.05, r = 0.56). The cost per day changed significantly over the different periods (χ(2)(2) = 24.00, p < 0.05). The variability and significantly lower costs of the latent period may influence cost effectiveness evaluations and consequently decision making, if not considered. Further studies analysing the influence of a latent period on the cost effectiveness of other treatments are warranted.