Post hoc power analysis: is it an informative and meaningful analysis?

Zhang, Yiran; Hedo, Rita; Rivera, Anna C.; Rull, Rudolph P.; Richardson, Sabrina M.; Tu, Xin

doi:10.1136/gpsych-2019-100069

Cited by 244 publications

(164 citation statements)

References 8 publications

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“…However, a higher rate of withdrawal than anticipated meant that 445 subjects were available for PP analysis. We did not perform a post hoc power estimation, as these are not considered useful [26].…”

Section: Discussionmentioning

confidence: 99%

Efficacy and Safety of Remogliflozin Etabonate, a New Sodium Glucose Co-Transporter-2 Inhibitor, in Patients with Type 2 Diabetes Mellitus: A 24-Week, Randomized, Double-Blind, Active-Controlled Trial

Dharmalingam

Aravind

Thacker

et al. 2020

Drugs

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Background Metformin is the first-line treatment for type 2 diabetes mellitus (T2DM), but many patients either cannot tolerate it or cannot achieve glycemic control with metformin alone, so treatment with other glucose-lowering agents in combination with metformin is frequently required. Remogliflozin etabonate, a novel agent, is an orally bioavailable prodrug of remogliflozin, which is a potent and selective sodium-glucose co-transporter-2 inhibitor. Objective Our objective was to evaluate the efficacy and safety of remogliflozin etabonate compared with dapagliflozin in subjects with T2DM in whom a stable dose of metformin as monotherapy was providing inadequate glycemic control. Methods A 24-week randomized, double-blind, double-dummy, active-controlled, three-arm, parallel-group, multicenter, phase III study was conducted in India. Patients aged ≥ 18 and ≤ 65 years diagnosed with T2DM, receiving metformin ≥ 1500 mg/day, and with glycated hemoglobin (HbA1c) levels ≥ 7 to ≤ 10% at screening were randomized into three groups. Every patient received metformin ≥ 1500 mg and either remogliflozin etabonate 100 mg twice daily (BID) (group 1, n = 225) or remogliflozin etabonate 250 mg BID (group 2, n = 241) or dapagliflozin 10 mg once daily (QD) in the morning and placebo QD in the evening (group 3, n = 146). The patients were followed-up at weeks 1 and 4 and at 4-week intervals thereafter until week 24. The endpoints included mean change in HbA1c (primary endpoint, noninferiority margin = 0.35), fasting plasma glucose (FPG), postprandial plasma glucose (PPG), bodyweight, blood pressure, and fasting lipids. Treatmentemergent adverse events (TEAEs), safety laboratory values, electrocardiogram, and vital signs were evaluated. Results Of 612 randomized patients, 167 (group 1), 175 (group 2), and 103 (group 3) patients with comparable baseline characteristics completed the study. Mean change ± standard error (SE) in HbA1c from baseline to week 24 was − 0.72 ± 0.09, − 0.77 ± 0.09, and − 0.58 ± 0.12% in groups 1, 2, and 3, respectively. The difference in mean HbA1c of group 1 versus group 3 (− 0.14%, 90% confidence interval [CI] − 0.38 to 0.10) and group 2 versus group 3 (− 0.19%; 90% CI − 0.42 to 0.05) was noninferior to that in group 3 (p < 0.001). No significant difference was found between group 1 or group 2 and group 3 in change in FPG, PPG, and bodyweight. The overall incidence of TEAEs was comparable across study groups (group 1 = 32.6%, group 2 = 34.4%, group 3 = 29.5%), including adverse events (AEs) of special interest (hypoglycemic events, urinary tract infection, genital fungal infection). Most TEAEs were mild to moderate in intensity, and no severe AEs were reported. Conclusion This study demonstrated the noninferiority of remogliflozin etabonate 100 and 250 mg compared with dapagliflozin, from the first analysis of an initial 612 patients. Remogliflozin etabonate therefore may be considered an effective and well-tolerated alternative treatment option for glycemic control in T2DM. Trial Registration CTRI/2017/07...

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Section: Discussionmentioning

confidence: 99%

Efficacy and Safety of Remogliflozin Etabonate, a New Sodium Glucose Co-Transporter-2 Inhibitor, in Patients with Type 2 Diabetes Mellitus: A 24-Week, Randomized, Double-Blind, Active-Controlled Trial

Dharmalingam

Aravind

Thacker

et al. 2020

Drugs

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“…A drop-out of 30% was added and final sample size required was 302. Post hoc power was calculated and was reported >85% (Cohen, 1988;Hertzog, 2008;Zhang et al, 2019).…”

Section: Sampling Procedures and Sample Sizementioning

confidence: 99%

Association of Disease Knowledge and Medication Adherence Among Out-Patients With Type 2 Diabetes Mellitus in Khobar, Saudi Arabia

et al. 2020

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Objective: The study aimed to evaluate the association between disease knowledge and medication adherence in patients with type 2 diabetes mellitus. Methods:A cross-sectional study was conducted for three months, in patients with type 2 diabetes who visited three community pharmacies located in Khobar, Saudi Arabia. Patients' disease knowledge and their adherence to medications were documented using Arabic versions of the Michigan Diabetes Knowledge Test and the General Medication Adherence Scale respectively. Data were analyzed through SPSS version 23. Chi-square test was used to report association of demographics with adherence. Spearman's rank correlation was employed to report the relationship among Hb A1c values, disease knowledge and adherence. Logistic regression model was utilized to report the determinants of medication adherence and their corresponding adjusted odds ratio. Study was approved by concerned ethical committee (IRB-UGS-2019-05-001).Results: A total of 318 patients consented to participate in the study. Mean Hb A1c value was 8.1%. A third of patients (N = 105, 33%) had high adherence and half of patients (N = 162, 50.9%) had disease knowledge between 51% -75%. A significantly weak-tomoderate and positive correlation (r = 0.221, p < 0.01) between medication adherence and disease knowledge was reported. Patients with >50% correct answers in the diabetes knowledge test questionnaire were more likely to be adherent to their medications (AOR 4.46, p < 0.01).Conclusion: Disease knowledge in most patients was average and half of patients had high-to-good adherence. Patients with better knowledge were 4 to 5 times more likely to have high adherence. This highlights the importance of patient education and awareness regarding medication adherence in managing diabetes.

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“…To understand the extent of these limitations, we carried out retrospective power analysis (using G * power) and observed that the correlation values obtained in Study 1 were within the critical range, but the beta errors exceeded the acceptable limit (Banerjee et al, 2009). Some researchers observe that the retrospective power analysis violates the key assumptions of a random sample (Zhang et al, 2019); however, the results of Study 1 should be interpreted within the limitation of small sample size and its impact on the power to detect significant correlations. Similarly, the non-random assignment of participants to the two groups also limits generalization; however, the yoga group represents a population that self-selects and seeks yoga training for cognitive benefits.…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

Enhancing Executive Control: Attention to Balance, Breath, and the Speed Versus Accuracy Tradeoff

Singh

Mutreja

2020

Front. Psychol.

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Malleability of executive control and its enhancement through yoga training is unclear. In Study 1, participants (yoga group; n = 27, mean = 23.27 years) were tested on executive control tasks pre-and post-8 weeks of yoga training. The training focused on attention to postural control during yoga asanas and respiratory control during pranayamabreathing (30 min each of postural and breath control training, biweekly). Yoga training was assessed via performance ratings as to how well a posture was executed and by examining errors that reflected inattention/failures in postural and breath control. We also explored whether attentional demands on motor and respiratory control were associated with three components of executive control (working memory, cognitive flexibility, and inhibition) during nine executive control tasks. Partial correlation results revealed that the three components of executive control might be differentially impacted by postural and breath control and selectively associated with either speed or accuracy (except for cognitive flexibility). Attentional demands influenced the link between postural, breath, and cognitive control. In Study 2, comparisons between a yoga group and a gendermatched control group (control group; n = 27, mean = 23.33 years) pointed toward higher working memory accuracy and a better speed-accuracy tradeoff in inhibitory control in the yoga group. A ceiling-practice effect was addressed by examining yoga practice learning (i.e., practice-induced change in postural and breath control reflected in ratings and errors) on executive control performance across two sets of tasks: repeatedly tested (pre-and post-8 weeks) and non-repeatedly tested (post-8 weeks). Attention to motor and respiratory control during yoga might be considered as a potential mechanism through which specific components of executive control in young adults might be enhanced potentially via altering of speed-accuracy tradeoff.

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Post hoc power analysis: is it an informative and meaningful analysis?

Cited by 244 publications

References 8 publications

Efficacy and Safety of Remogliflozin Etabonate, a New Sodium Glucose Co-Transporter-2 Inhibitor, in Patients with Type 2 Diabetes Mellitus: A 24-Week, Randomized, Double-Blind, Active-Controlled Trial

Efficacy and Safety of Remogliflozin Etabonate, a New Sodium Glucose Co-Transporter-2 Inhibitor, in Patients with Type 2 Diabetes Mellitus: A 24-Week, Randomized, Double-Blind, Active-Controlled Trial

Association of Disease Knowledge and Medication Adherence Among Out-Patients With Type 2 Diabetes Mellitus in Khobar, Saudi Arabia

Enhancing Executive Control: Attention to Balance, Breath, and the Speed Versus Accuracy Tradeoff

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