Switching from NSAIDs to paracetamol: a series of n of 1 trials for individual patients with osteoarthritis

Status of N-of-1 Trials in Chronic Pain Management: A Narrative Review

N-of-1 trials are randomized controlled clinical trials conducted exclusively on a single patient. The ultimate aim of N-of-1 trials is to optimize a strategy in a particular individual. Chronic pain is a common but refractory clinical problem. Its diverse etiologies and broad variations among patients often lead to the requirement of individualizing medicine. Thus, chronic pain represents a classical condition for N-of-1 clinical trials. Studies have indicated that N-of-1 benefits patients with chronic pain, multiple comorbidities, and uncertain variations during therapies; however, this approach it is not yet adopted as the first choice in pain clinics. To dissect the current status of N-of-1 in chronic pain management, as well as the limitations for its implementation, we herein studied all N-of-1 studies related to chronic pain by searching three major databases (PubMed, ClinicalTrial.gov, Cochrane Library) for publications between 1985 and 2020. Of 35 eligibility papers, 19 were selected for analysis. Results confirmed that N-of-1 trials have solved the refractory cases including osteoarthritis, chronic musculoskeletal pain, and neuropathic pain; however, none of the trials dealt with cancer pain. Longer time and more efforts are needed from investigators when carrying out N-of-1 trials, which inevitably result in implementation difficulties. Of note, all recruited trials were conducted in developed countries. As mobile devices have been introduced and protocols improve, renewed interest in the implementation of N-of-1 trials will occur. Collectively, a previously underestimated conflict between "precision medicine" and "poor implementation" has put N-of-1 in a challenging position for chronic pain management.

Designing Robust N-of-1 Studies for Precision Medicine: Simulation Study and Design Recommendations

Background

Recent advances in molecular biology, sensors, and digital medicine have led to an explosion of products and services for high-resolution monitoring of individual health. The N-of-1 study has emerged as an important methodological tool for harnessing these new data sources, enabling researchers to compare the effectiveness of health interventions at the level of a single individual.

Objective

N-of-1 studies are susceptible to several design flaws. We developed a model that generates realistic data for N-of-1 studies to enable researchers to optimize study designs in advance.

Methods

Our stochastic time-series model simulates an N-of-1 study, incorporating all study-relevant effects, such as carryover and wash-in effects, as well as various sources of noise. The model can be used to produce realistic simulated data for a near-infinite number of N-of-1 study designs, treatment profiles, and patient characteristics.

Results

Using simulation, we demonstrate how the number of treatment blocks, ordering of treatments within blocks, duration of each treatment, and sampling frequency affect our ability to detect true differences in treatment efficacy. We provide a set of recommendations for study designs on the basis of treatment, outcomes, and instrument parameters, and make our simulation software publicly available for use by the precision medicine community.

Conclusions

Simulation can facilitate rapid optimization of N-of-1 study designs and increase the likelihood of study success while minimizing participant burden.

N-of-1 Design and Its Applications to Personalized Treatment Studies

N-of-1 trial is a type of clinical trial which has been applied in chronic recurrent conditions that require long-term non-curative treatment. In this type of trials, each patient will be randomly assigned to one of the treatment sequences and repeatedly crossed over two or more treatments of interests. Through this cross-comparing method (cross-over phase), investigator can identify an optimal treatment (medicine or therapy) for the patient and treat the patient with the optimal treatment in an extension phase. This design could efficiently reduce the placebo effect, which is often seen in clinical trials, and maximize the true treatment effect. This type of design has been used in some traditional Chinese medicine (TCM) clinical trials lately. However, it brings some challenges for collecting and analyzing the data. Research on statistical methodology of this type of design is rarely found in the literature. The goal of this research is to discuss the application of the N-of-1 design to personalized treatment studies. We will demonstrate a real study conducted in TCM and present some theoretical and simulation results.

CONSORT extension for reporting N-of-1 trials (CENT) 2015: explanation and elaboration

N-of-1 trials are a useful tool for clinicians who want to determine the effectiveness of a treatment in a particular individual. The reporting of N-of-1 trials has been variable and incomplete, hindering their usefulness in clinical decision making and by future researchers. This document presents the CONSORT (Consolidated Standards of Reporting Trials) extension for N-of-1 trials (CENT 2015). CENT 2015 extends the CONSORT 2010 guidance to facilitate the preparation and appraisal of reports of an individual N-of-1 trial or a series of prospectively planned, multiple, crossover N-of-1 trials. CENT 2015 elaborates on 14 items of the CONSORT 2010 checklist, totalling 25 checklist items (44 sub-items), and recommends diagrams to help authors document the progress of one participant through a trial or more than one participant through a trial or series of trials, as applicable. Examples of good reporting and evidence based rationale for CENT 2015 checklist items are provided.

N-of-1 trials in the medical literature: a systematic review

BACKGROUND

N-of-1 trials (multiple crossover studies conducted in single individuals) may be ideal for determining individual treatment effects and as a tool to estimate heterogeneity of treatment effects (HTE) in a population. However, comprehensive data on n-of-1 trial methodology and analysis is lacking. We performed this study to describe n-of-1 trial characteristics, examine treatment changes resulting from n-of-1 trial participation, and to determine if trial reporting is adequate for estimating HTE.

METHODS

We undertook a systematic review of n-of-1 trials published between 1985 and December 2010. Included trials were those having individual treatment episodes as the unit of randomization and reporting individual-specific treatment effects. We abstracted trial characteristics, treatment change information, and analytic methods.

RESULTS

We included 108 trials reporting on 2154 participants. Approximately half (49%) of the trials used a statistical cutoff to determine a superior treatment, whereas the remainder used a graphical comparison (25%) or a clinical significance cutoff (20%). Sixty-seven trials, reporting on 488 people, provided treatment change information: 54% of participants had subsequent treatment decisions consistent with the results of the trial, 8% had decisions inconsistent with trial results, and 38% had ambiguous results. Less than half of the trials (45%) reported adequate information to facilitate the calculation of HTE.

CONCLUSION

N-of-1 trials are a useful tool for enhancing therapeutic precision in a range of conditions and should be conducted more often. To facilitate future meta-analysis, and the estimation of HTE, researchers reporting n-of-1 trial results should clearly describe individual data.

The n-of-1 clinical trial: the ultimate strategy for individualizing medicine?

N-of-1 or single subject clinical trials consider an individual patient as the sole unit of observation in a study investigating the efficacy or side-effect profiles of different interventions. The ultimate goal of an n-of-1 trial is to determine the optimal or best intervention for an individual patient using objective data-driven criteria. Such trials can leverage study design and statistical techniques associated with standard population-based clinical trials, including randomization, washout and crossover periods, as well as placebo controls. Despite their obvious appeal and wide use in educational settings, n-of-1 trials have been used sparingly in medical and general clinical settings. We briefly review the history, motivation and design of n-of-1 trials and emphasize the great utility of modern wireless medical monitoring devices in their execution. We ultimately argue that n-of-1 trials demand serious attention among the health research and clinical care communities given the contemporary focus on individualized medicine.

Long-term changes in management following n-of-1 trials of stimulants in attention-deficit/hyperactivity disorder

OBJECTIVE

Our objective was to evaluate the long-term impact of n-of-1 trials-within-patient randomised, double-blind, cross-over comparisons of stimulant versus placebo or stimulant-on ADHD management.

METHODS

Telephone surveys at 3, 6 and 12 months. Main outcome measures included (1) changes in treatment before and after the n-of-1 trial, (2) congruence of management at follow-up with trial result, (3) reasons for any non-congruence, and (4) persistence of the joint patient-doctor decision over 12 months. Patients were children with clinically diagnosed ADHD, aged 5-16 years.

RESULTS

A total of 76 patients were followed up; 12 months' data were available for 67 (88%). Management changed from baseline for 46, 48 and 51% at 3, 6 and 12 months respectively. Most responders, 21/37 (57%), remained on the same stimulant at 12 months, compared to 9/24 (37%) non-responders. Of the remaining non-responders, 15/24 (62%) either switched (2/24, 8%) or ceased stimulants (13/24, 54%). The rate of congruence with the test result was 45/65 (69%) at 3 months, 44/67 (66%) at 6 months and 40/67 (60%) at 12 months. Persistence with the post-trial decision over 12 months was high (79-85%) whether the decision was to continue or to cease stimulants.

CONCLUSIONS

Although not conclusive because there was no control group, our results suggest that n-of-1 trials may improve rational treatment of ADHD.

Osteoarthritis: rational approach to treating the individual

Osteoarthritis (OA) is the most common form of joint disease and the leading cause of pain and physical disability in older people. Risk factors for incidence and progression of osteoarthritis vary considerably according to the type of joint. Disease assessment is difficult and the relationship between the radiographic severity of joint damage and the incidence and severity of pain is only modest. Psychosocial and socio-economic factors play an important role. This chapter will discuss four main guiding principles to the management of OA: (1) to avoid overtreating people with mild symptoms; (2) to attempt to avoid doing more harm than good ('primum non nocere'); (3) to base patient management on the severity of pain, disability and distress, and not on the severity of joint damage or radiographic change; and (4) to start with advice about simple measures that patients can take to help themselves, and only progress to interventions that require supervision or specialist knowledge if simple measures fail. Effect sizes derived from meta-analyses of large randomized trials in OA are only small to moderate for most therapeutic interventions, but they are still valuable for patients and clinically relevant for physicians. Joint replacement may be the only option with a large effect size, but is only appropriate for the relatively small number of people with OA who have advanced disease and severe symptoms. The key to successful management involves patient and health professionals working together to develop optimal treatment strategies for the individual.

Use of double-blind placebo-controlled N-of-1 trials among stimulant-treated youths in The Netherlands: a descriptive study

OBJECTIVES

An N-of-1 trial is a double-blind placebo-controlled randomized trial to objectively and systematically evaluate the individual's response. This approach seems extraordinarily suitable for assessing the efficacy of stimulants in the treatment of attention deficit hyperactivity disorder (ADHD). The aim is to examine the use of N-of-1 trials among youths in the Netherlands, the protocols used, and the continuation of stimulant treatment thereafter.

METHODS

Physicians requesting N-of-1 trials with stimulants were interviewed about their rationale and protocol. Prevalence and continuation were investigated by extracting N-of-1 trials among youths <20 years of age from a large pharmacy dispensing database for 2000-2004.

RESULTS

The main purpose of N-of-1 trials mentioned by physicians was the assessing of individuals' response and dose-finding. Trial length, dosing schedule and efficacy assessment differed per physician. Trials consisted of a maximum of two treatment periods per dose. The annual percentage of youths starting stimulant treatment with an N-of-1 trial fluctuated between 0.6% (3/462) and 3.3% (10/301). No statistical significant difference could be detected between the continuation of stimulant treatment with or without an N-of-1 trial (p = 0.71).

CONCLUSIONS

N-of-1 trials with stimulants are infrequently and not optimally used in the Netherlands. The results of N-of-1 protocols described by physicians are of questionable value, due to the small number of treatment periods per dose. More uniformity in the protocols would make it easier to encompass the N-of-1 methodology in physicians' daily practice.

Conducting research in individual patients: lessons learnt from two series of N-of-1 trials

Background

Double-blind randomised N-of-1 trials (N-of-1 trials) may help with decisions concerning treatment when there is doubt regarding the effectiveness and suitability of medication for individual patients. The patient is his or her own control, and receives the experimental and the control treatment during several periods of time in random order. Reports of N-of-1 trials are still relatively scarce, and the research methodology is not as firmly established as that of RCTs. Recently, we have conducted two series of N-of-1 trials in general practice. Before, during, and after data-collection, difficulties regarding outcome assessment, analysis of the results, the withdrawal of patients, and the follow-up had to be dealt with. These difficulties are described and our solutions are discussed.

Discussion

To prevent or anticipate difficulties in N-of-1 trials, we argue that that it is important to individualise the outcome measures, and to carefully consider the objective, type of randomisation and the analysis. It is recommended to use the same dosages and dosage forms that the patient used before the trial, to start the trial with a run-in period, to formulate both general and individualised decision rules regarding the efficacy of treatment, to adjust treatment policies immediately after the trial, and to provide adequate instructions and support if treatment is adjusted.

Summary

Because of the specific characteristics of N-of-1 trials it is difficult to formulate general 'how to do it' guidelines for designing N-of-1 trials. However, when the design of each N-of-1 trial is tailored to the specific characteristics of each individual patient and the underlying medical problem, most difficulties in N-of-1 trials can be prevented or overcome. In this way, N-of-1 trials may be of help when deciding on drug treatment for individual patients.

The role of paracetamol in chronic pain: an evidence-based approach

Chronic pain is a significant public health burden. Several international guidelines and influential reviews recommend the use of paracetamol (acetaminophen) as the first-line analgesic of choice for the management of chronic pain. These recommendations are based largely on the balance of evidence, which favorably demonstrates the efficacy, safety, and low cost of paracetamol relative to other analgesics.A decade ago, March et al suggested that because of the dangers associated with conventional nonsteroidal antiinflammatory (NSAID) use, particularly in the elderly, they should ideally not be used without an individual n-of-1 trial to show that they are more effective than paracetamol. Today, the results of our investigations into the individualization of pain management options continue to support this suggestion. Based on the data available to date, it still seems prudent to use NSAIDs only in those patients in whom there is good evidence of improved efficacy over paracetamol. In patients with chronic pain, paracetamol can play an important role as an NSAID sparer, with resultant benefits in terms of reduced adverse effects and cost savings.

Do individualized medication effectiveness tests (n-of-1 trials) change clinical decisions about which drugs to use for osteoarthritis and chronic pain?

To assess the impact of individualized medication effectiveness tests (IMETs, or n-of-1 trials), on patients' short-term decision making about medications for chronic pain. Survey evaluation of patients undergoing a double-blind, crossover comparison of drug versus placebo, drug versus drug, or drug versus drug combination using paracetamol and ibuprofen in 3 pairs of treatment periods, randomized within pairs. General practice patients (supplemented by a few from 2 tertiary pain clinics) with either chronic pain (> or =3 months), or osteoarthritis (with pain for > or =1 month) severe enough to warrant consideration of long-term nonsteroidal antiinflammatory drug (NSAID) use but for whom there was doubt about the efficacy of NSAID or alternative. Pain and stiffness in sites nominated by the patient, global pain, use of escape analgesia, and side effects. Of 116 IMETs started, 71 were completed. Drug management changed for 46 of 71 (65%). The most common change was to add paracetamol or to substitute the NSAID or COX-2 inhibitor with paracetamol (25 of 71 patients and 54% of changes). Of the 37 who were using NSAIDs or COX-2 inhibitors before the IMET, 12 (32%) ceased these afterward. Paracetamol was as effective or more effective than ibuprofen in 37 (68%) of the 54 IMETs directly comparing these drugs. IMETs provide useful information for clinical decisions. Paracetamol continues to be useful for patients with chronic pain whose optimal drug choice is in doubt. Our results provide a new (individual) perspective on the well-known recommendation for paracetamol as first-line treatment for chronic pain and demonstrate that it is feasible to provide IMETs nationally by mail and telephone.

First line treatment of knee osteoarthritis in outpatients in France: adherence to the EULAR 2000 recommendations and factors influencing adherence

OBJECTIVES

To document adherence to two parts of the EULAR 2000 recommendations for knee osteoarthritis, concerning non-pharmacological and pharmacological first line management; and to identify factors influencing adherence to the recommendations.

METHODS

In a prospective study, 1030 randomly selected French general practitioners completed questionnaires about three unselected outpatients with osteoarthritis, and about their own practice, knowledge, and agreement with the EULAR 2000 recommendations. Percentages of adherence of their prescriptions to both parts of the recommendation were calculated, and probabilities of non-adherence analysed in relation to patient and physician related characteristics, using multilevel logistic regression analysis.

RESULTS

Data were obtained from 967 physicians and 2430 patients. The EULAR 2000 recommendations were familiar to 79% of the GPs; 99% agreed with the non-pharmacological part and 97% with the pharmacological part. Adherence to the two parts was 74.8% and 73.6%, but 54.2% for both together. Factors increasing adherence to the non-pharmacological recommendation were patient body mass index >35 kg/m(2) (odds ratio 0.11 (95% confidence interval, 0.06 to 0.21)), patient's stated preference for a treatment (OR 0.43 (0.55 to 0.97)), and physician's regular continuance of medical education (OR 0.76 (0.59 to 0.98)); patient's age and duration of symptoms decreased adherence. Factors increasing adherence to the pharmacological recommendation were gastrointestinal disease (OR 0.50 (0.35 to 0.72)) and physician's knowledge of the EULAR recommendations (OR 0.75 (0.60 to 0.93)).

CONCLUSIONS

Although most physicians agreed with the EULAR 2000 recommendations, adherence was only approximately 75% for each of the non-pharmacological and pharmacological recommendations and 54% for both together.

An Overview of Hip Injuries in Running

Running has steadily gained in worldwide popularity and is the primary exercise modality for many individuals of all ages. Its low cost, versatility, convenience and related health benefits appeal to men and women of broad cultural, ethnic and economic backgrounds. With more children and adults participating in recreational and competitive running, the incidence of injuries has steadily increased. Most running-related injuries affecting the lower extremities are due to preventable training errors, and some may necessitate medical evaluation or a significant reduction in training. Hip injuries in runners are due to interactions of intrinsic and extrinsic factors that adversely affect the complex regional anatomy. Acute or chronic hip pain presents a diagnostic and therapeutic challenge because the vague, nonspecific symptoms and signs may originate from local, regional or distant foci. Muscle strains and tendonitis are the most common aetiologies of hip pain and typically result from sudden acceleration/deceleration manoeuvres, direction changes or eccentric contractions. Apophysitis and avulsion fractures may affect younger runners and produce localised pain at muscle attachment sites. Iliotibial band syndrome is a common cause of lateral hip and knee symptoms characterised by sharp or burning pain that is exacerbated by activity. Bursitis, due to repetitive activity or acute trauma, may affect the trochanteric, ischial or iliopectineal bursae. Hip osteoarthritis may also produce persistent pain that worsens with running. Stress fractures are potentially serious conditions that affect women more frequently than men. Snapping hip syndrome is a benign condition that results from tight connective tissues' passing repeatedly over the greater trochanter, anterior hip capsule, lesser trochanter, femoral head or iliopectineal eminence. Acetabular labral tears, sports hernias and nerve entrapment syndromes are also potential causes of persistent hip pain in runners. Treatment of hip pain in running should focus not only on addressing the symptoms but also identifying the underlying conditions that precipitated the injury. Injury prevention and comprehensive rehabilitation are essential, since prior hip injuries increase the risk of subsequent ones. Coaches, trainers and medical personal who care for runners should advocate running regimens, surfaces, shoes, technique and individualised conditioning programmes that minimise the risk of initial or recurrent hip injuries.