The number needed to treat and relevant between-trial comparisons of competing interventions

Concept of the Number Needed to Treat for the Analysis of Pain Relief Outcomes in Patients Treated with Spinal Cord Stimulation

In the rapidly evolving field of spinal cord stimulation (SCS), measures of treatment effects are needed to help understand the benefits of new therapies. The present article elaborates the number needed to treat (NNT) concept and applies it to the SCS field. We reviewed the basic theory of the NNT, its calculation method, and its application to historical controlled trials of SCS. We searched the literature for controlled studies with ≥20 implanted SCS patients with chronic axial back and/or leg pain followed for ≥3 months and a reported responder rate defined as ≥50% pain relief. Relevant data necessary to estimate the NNT were extracted from the included articles. In total, 12 of 1616 records were eligible for inclusion. The records reported 10 clinical studies, including 7 randomized controlled trials, 2 randomized crossover trials, and 1 controlled cohort study. The studies investigated traditional SCS and more recently developed SCS modalities, including 10 kHz SCS. In conclusion, the NNT estimate may help SCS stakeholders better understand the effect size difference between compared treatments; however, interpretation of any NNT should take into account its full context. In addition, comparisons across trials of different therapies should be avoided since they are prone to interpretation biases.

Association of Real-time Continuous Glucose Monitoring With Glycemic Control and Acute Metabolic Events Among Patients With Insulin-Treated Diabetes

IMPORTANCE

Continuous glucose monitoring (CGM) is recommended for patients with type 1 diabetes; observational evidence for CGM in patients with insulin-treated type 2 diabetes is lacking.

OBJECTIVE

To estimate clinical outcomes of real-time CGM initiation.

DESIGN, SETTING, AND PARTICIPANTS

Exploratory retrospective cohort study of changes in outcomes associated with real-time CGM initiation, estimated using a difference-in-differences analysis. A total of 41 753 participants with insulin-treated diabetes (5673 type 1; 36 080 type 2) receiving care from a Northern California integrated health care delivery system (2014-2019), being treated with insulin, self-monitoring their blood glucose levels, and having no prior CGM use were included.

EXPOSURES

Initiation vs noninitiation of real-time CGM (reference group).

MAIN OUTCOMES AND MEASURES

Ten end points measured during the 12 months before and 12 months after baseline: hemoglobin A1c (HbA1c); hypoglycemia (emergency department or hospital utilization); hyperglycemia (emergency department or hospital utilization); HbA1c levels lower than 7%, lower than 8%, and higher than 9%; 1 emergency department encounter or more for any reason; 1 hospitalization or more for any reason; and number of outpatient visits and telephone visits.

RESULTS

The real-time CGM initiators included 3806 patients (mean age, 42.4 years [SD, 19.9 years]; 51% female; 91% type 1, 9% type 2); the noninitiators included 37 947 patients (mean age, 63.4 years [SD, 13.4 years]; 49% female; 6% type 1, 94% type 2). The prebaseline mean HbA1c was lower among real-time CGM initiators than among noninitiators, but real-time CGM initiators had higher prebaseline rates of hypoglycemia and hyperglycemia. Mean HbA1c declined among real-time CGM initiators from 8.17% to 7.76% and from 8.28% to 8.19% among noninitiators (adjusted difference-in-differences estimate, -0.40%; 95% CI, -0.48% to -0.32%; P < .001). Hypoglycemia rates declined among real-time CGM initiators from 5.1% to 3.0% and increased among noninitiators from 1.9% to 2.3% (difference-in-differences estimate, -2.7%; 95% CI, -4.4% to -1.1%; P = .001). There were also statistically significant differences in the adjusted net changes in the proportion of patients with HbA1c lower than 7% (adjusted difference-in-differences estimate, 9.6%; 95% CI, 7.1% to 12.2%; P < .001), lower than 8% (adjusted difference-in-differences estimate, 13.1%; 95% CI, 10.2% to 16.1%; P < .001), and higher than 9% (adjusted difference-in-differences estimate, -7.1%; 95% CI, -9.5% to -4.6%; P < .001) and in the number of outpatient visits (adjusted difference-in-differences estimate, -0.4; 95% CI, -0.6 to -0.2; P < .001) and telephone visits (adjusted difference-in-differences estimate, 1.1; 95% CI, 0.8 to 1.4; P < .001). Initiation of real-time CGM was not associated with statistically significant changes in rates of hyperglycemia, emergency department visits for any reason, or hospitalizations for any reason.

CONCLUSIONS AND RELEVANCE

In this retrospective cohort study, insulin-treated patients with diabetes selected by physicians for real-time continuous glucose monitoring compared with noninitiators had significant improvements in hemoglobin A1c and reductions in emergency department visits and hospitalizations for hypoglycemia, but no significant change in emergency department visits or hospitalizations for hyperglycemia or for any reason. Because of the observational study design, findings may have been susceptible to selection bias.

Immediate clinical benefits of combining therapeutic exercise and interferential therapy in adults with chronic neck pain: a randomized controlled trial

BACKGROUND

Therapeutic exercise is highly recommended for the management of non-specific neck pain and has shown promising results combined with interferential current therapy. Yet, the clinical relevance of the pooled effect of these approaches remains uncertain.

AIM

To investigate the immediate clinical effect size of combining therapeutic exercise and interferential therapy, compared with the isolated use of therapeutic exercise, in adults with chronic non-specific neck pain.

DESIGN

Randomized, single-blinded, controlled, superiority trial.

SETTING

Outpatients, primary care center.

POPULATION

Forty-nine adults with chronic non-specific neck pain.

METHODS

Participants with neck pain (grades I or II) lasting for more than 12 weeks were allocated to a therapeutic exercise plus interferential currents group (n = 25) or to a therapeutic exercise only group (n = 24). All individuals underwent treatment 5 times a week for 2 weeks. The primary outcome was current neck pain intensity (11-point numeric pain rating scale). Secondary outcomes included neck disability (Neck Disability Index) and active cervical range-of-movement (CROM device). Measurements were taken at baseline and immediately after treatment. An intention-to-treat analysis was carried out. To quantify the effect size of the interventions, the relative risk, the absolute and relative risk reduction, and the number needed to treat were calculated.

RESULTS

A significant time*group effect was found for pain intensity, disability, and neck flexion and right rotation (all, p < 0.05). In the analysis for treatment benefit, the number needed to treat was 2 (95% CI: 2 to 4, p < 0.001) for neck pain and disability, and 3 (95% CI: 2 to 11, p = 0.029) for neck flexion.

CONCLUSIONS

Adding interferential therapy to therapeutic exercise is clinically more effective than therapeutic exercise alone to immediately improve neck pain and disability, but not active cervical range-of-movement, in adults with persistent neck pain.

CLINICAL REHABILITATION IMPACT

Our results suggest that this multimodal intervention can be a useful strategy for rehabilitation of patients with non-specific neck pain. This is the first study on this topic reporting findings in terms of clinical relevance, which is key to transfer research evidence into practice.