Sample Size Considerations in Designing Studies with Intra-oral Models

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 819-821 ◽  
Author(s):  
G.K. Stookey ◽  
B.P. Katz ◽  
B.B. Beiswanger ◽  
A.J. Dunipace
Keyword(s):  
Sample Size ◽  
Clinical Efficacy ◽  
Study Design ◽  
Relevant Information ◽  
Preclinical Models ◽  
Within Subjects ◽  
Clinical Models ◽  
Sources Of Variation ◽  
Uptake Data ◽  
Proper Consideration

Especially during recent years, the use of pre-clinical models for predicting the efficacy of fluoride systems has assumed greater importance within the scientific community. Originally utilized primarily to screen experimental fluoride delivery systems, preclinical models are now being considered as predictors of clinical efficacy in lieu of controlled clinical caries trials. Of the various preclinical models presently available, human intra-oral models have the greatest potential for reflecting intended usage conditions and therefore may be the most meaningful models for predicting clinical efficacy. However, only with the proper consideration of numerous critical variables can studies using intra-oral models be appropriately designed to achieve the desired objectives. Clearly, these models must provide relevant information in a manner which reflects clinically established cariostatic activity and be capable of detecting established differences in the amount of cariostatic activity, i.e., dose-response effects. Three sources of variation must be considered before an appropriate study design and sample size can be chosen. Based on fluoride uptake data from an intra-oral model with proximally-located enamel specimens, estimates of variation among subjects, within subjects, and among specimens within subjects were obtained. Multiple specimens per panelist do not affect the first two sources of variation. Thus, the number of panelists, and not the number of specimens, is of primary importance when pre-test data are used to choose the appropriate study design and calculate the required sample size.

scholarly journals CLINICAL EFFICACY OF ARDHAMATRIKA BASTI IN GRIDHRASI

2022 ◽  
Vol 12 (6) ◽  
pp. 50-55
Author(s):  
Aiyanna PP ◽  
Vishnu Prasad V ◽  
Pradeep JM
Keyword(s):  
Clinical Trial ◽  
Sample Size ◽  
Clinical Efficacy ◽  
Study Design ◽  
Marked Improvement ◽  
Selection Criteria ◽  
Assessment Criteria ◽  
Treatment Modalities ◽  
Practical Utility

Gridhrasi, one among the Nanatmaja Vikara, specific Nidana and Samprapti is not explained in classics so that the general Vata Vyadi Nidhana Samprapthi can be considered. The Chikitsa of Gridhrasi includes Sneha, Sweda, Bastikarma and Agni karma. Generally, Basti is the best line of treatment for Vata dosa. References from Acharya Charaka also explain Basti as one of the treatment modalities. With the support of Niruhadikara in Chakradhatta, we have the reference of Ardhamatrika Basti, which is one among Kashaya Basti, here he explains the practical utility along with many added benefits of Bala, Varna, Vrushatha and Pumsavanathva which gifted by Atreya Maharshi. Ardhamatrika Basti, one among Madhutailika Basti (having an equal quantity of Madhu and Taila), can be clinically explored where neither Parihara Kala nor Purva karma like Sneha, Sweda are necessary. The study design selected for the study was a comprehensive clinical trial. The sample size for the present study was 30 patients suffering from Gridrasi as per the selection criteria. Patients were randomly selected irrespective of sex and were treated with Ardhmatrika Basti as a yoga Basti for eight days. Among 30 patients taken for study, marked improvement in the symptomatology of the disease is obtained. 26.7% of patients got complete Shamana, 36.7% achieved Prayika shamana, 30% reported Amsika shamana, and 6.6% had Kinchit shamana. In the assessment criteria taken in patients, Ruja BT - 2.68 after follow up reduced to 1.8, Spandana BT - 2.38 after follow up reduced to 1.73, Sakthana Utksepa-nigraha BT - 2.82 after follow up reduced to 1.58, Gourava BT - 2.5 after follow up reduced to 1.7, Arochaka BT - 2.22 after follow up reduced to 1.87. This result shows that the present study of Ardhamatrika Basti has given a marked improvement in treating Gridhrasi.

The most frequently asked question to a statistician: The sample size

2017 ◽  
Vol 23 (5) ◽  
pp. 644-646 ◽  
Author(s):  
Maria Pia Sormani
Keyword(s):  
Clinical Study ◽  
Sample Size ◽  
Study Design ◽  
Treatment Effect ◽  
Sample Size Calculation ◽  
Ethical Implications ◽  
Number Of Patients ◽  
Reducing Costs ◽  
Correct Size

The calculation of the sample size needed for a clinical study is the challenge most frequently put to statisticians, and it is one of the most relevant issues in the study design. The correct size of the study sample optimizes the number of patients needed to get the result, that is, to detect the minimum treatment effect that is clinically relevant. Minimizing the sample size of a study has the advantage of reducing costs, enhancing feasibility, and also has ethical implications. In this brief report, I will explore the main concepts on which the sample size calculation is based.

Reproducibility of fluctuating asymmetry measurements in plants: Sources of variation and implications for study design

2017 ◽  
Vol 73 ◽  
pp. 733-740 ◽  
Author(s):  
Mikhail V. Kozlov ◽  
Tatiana Cornelissen ◽  
Dmitry E. Gavrikov ◽  
Mikhail A. Kunavin ◽  
Ang Dawa Lama ◽  
...  
Keyword(s):  
Study Design ◽  
Fluctuating Asymmetry ◽  
Sources Of Variation

data a; * significance level; a=0.05; * variance of difference of two observations on the log scale; * sigmaW = within-subjects standard deviation; sigmaW=0.355; s=sqrt(2)*sigmaW; * total number of subjects (needs to be a multiple of 2); n=58; * error degrees of freedom for AB/BA cross-over with n subjects in total; n2=n-2; * ratio = mu_T/mu_R; ratio=1.00; run; data b; set a; * calculate power; t1=tinv(1-a,n-2); t2=-t1; nc1=(sqrt(n))*((log(ratio)-log(0.8))/s); nc2=(sqrt(n))*((log(ratio)-log(1.25))/s); df=(sqrt(n-2))*((nc1-nc2)/(2*t1)); prob1=probt(t1,df,nc1); prob2=probt(t2,df,nc2); answer=prob2-prob1; power=answer*100; run; proc print data=b; run; As an example of using this SAS code, suppose µ = 1, σ = 0.355, α = 0.05 and n = 58. The power (as a percentage) is calculated as 90.4. The required number of subjects to achieve a given power can easily be obtained by trial and error using a selection of values of n. An alternative approach is to use trial and error directly on the sample size n for a given power. For more on this see Phillips (1990) and Diletti et al. (1991), for example. 7.4 Individual bioequivalence As noted in Section 7.1, individual bioequivalence (IBE) is a criterion for deciding if a patient who is currently being treated with R can be

2003 ◽  
pp. 362-362
Keyword(s):  
Standard Deviation ◽  
Sample Size ◽  
Degrees Of Freedom ◽  
Trial And Error ◽  
Significance Level ◽  
Individual Bioequivalence ◽  
Alternative Approach ◽  
Within Subjects ◽  
Log Ratio ◽  
Selection Of

Frequency of Sensorineural Hearing Loss among Children with Bacterial Meningitis

2021 ◽  
Vol 15 (8) ◽  
pp. 1827-1828
Author(s):  
Faiza Gohar ◽  
Syed Sajid Munir ◽  
Sami Ul Haq
Keyword(s):  
Hearing Loss ◽  
Bacterial Meningitis ◽  
Sensorineural Hearing Loss ◽  
Sample Size ◽  
Study Design ◽  
Teaching Hospital ◽  
Sensorineural Hearing ◽  
Acute Bacterial Meningitis ◽  
Cross Sectional ◽  
Hearing Assessment

Aim: Frequency of sensorineural hearing loss among children presenting with acute bacterial meningitis. Study design: Pediatric wards of Khyber Teaching Hospital, Peshawar with the help of audiology department of Khyber teaching hospital, Peshawar Study design & duration: Descriptive cross sectional study. 5 months from 23/10/2018 to 23/03/2019. Sample size: Sample size was 149 using 44.4% proportions SNHL among children with bacterial meningitis, 95% confidence level and 8% absolute precision using WHO sample size calculations. Methodology: 149 cases i.e. 90 males and 59 females were included with age of 02 to 144 months. All were with diagnosis of bacterial meningitis. Lab tests and CSF examination was performed. The assessment of hearing was done before discharge in the form of BERA and PTA. All findings of hearing assessment was entered in Performa. Results: In the study, mean± SD of age was 28± 35.7. Moreover, 60.4% were males and 39.6% were females. 10(6.7%) of the 149 cases have sensorineural hearing loss while 139(93.3%) were having normal on hearing assessment. Conclusion: Sensorineural hearing loss in patients with bacterial meningitis was 6.7%. Keywords: Sensorineural Hearing Loss, Meningitis, Bacterial Meningitis

Genotype-based enrichment study design for minimizing the sample size in bioequivalence studies using tolterodine and CYP2D6 genotype

2019 ◽  
Vol 57 (02) ◽  
pp. 110-116 ◽  
Author(s):  
Minkyung Oh ◽  
Chang-Woo Yeo ◽  
Ho-Sook Kim ◽  
Jihong Shon ◽  
Jae-Gook Shin
Keyword(s):  
Sample Size ◽  
Study Design ◽  
Cyp2d6 Genotype

Hydroxyurea for β-Thalassemia Major: A Meta-Analysis

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4894-4894 ◽  
Author(s):  
Ali H. Algiraigri ◽  
Nicola A. Wright ◽  
Aliya Kassam
Keyword(s):  
Sample Size ◽  
Clinical Efficacy ◽  
Observational Studies ◽  
Response Rate ◽  
Meta Analysis ◽  
Thalassemia Major ◽  
Organ Damage ◽  
Controlled Trials ◽  
Cochrane Central Register

Abstract Background β-thalassemia major (β-TM) is one of the most common inherited diseases worldwide, characterized by a reduced ability to produce hemoglobin resulting in life-long transfusion-dependent anemia. Chronic transfusions carry significant risks such as infection, and result in iron overload that can cause significant multisystem organ damage. Hydroxyurea, an oral chemotherapeutic drug, is anticipated to decrease the need for transfusions, either completely or partially by raising hemoglobin levels and thus decreasing the short and long term complications of chronic transfusions. Objectives To evaluate the clinical efficacy and safety of hydroxyurea in β-thalassemia major (β-TM) patients of any age. Search strategy We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ongoing trials registers, and major preceding conferences. Hand searches were also conducted using reference lists from primary studies. All searches were updated to June 5, 2014. Selection criteria Randomized controlled trials (RCTs) and observational studies (sample size ≥ 5) assessing the clinical efficacy of hydroxyurea alone for three months or longer, for the treatment of patients with β-TM were included. Data collection and analysis Two authors acted as reviewers and independently assessed study quality and extracted data from the included studies. Authors of included studies were contacted if further information was required. β-TM includes the classical β-TM as well as severe hemoglobin E/β thalassemia, both of which are characterized by lifelong transfusion needs. The effect size was estimated as a proportion (those showing response to treatment over the total number treated) and reported as overall response rate (ORR) or complete response rate (CRR). ORR was defined as ≥ 50% reduction in transfusion need and CRR was defined as complete cessation of regular transfusion. All data was analyzed using Stata, Version 13.0. Results A total of 10 observational studies involving 620 patients were included. Hydroxyurea was associated with a statistically significant decrease in transfusion need with CRR of 36% (95% CI, 23-50%) and ORR of 66% (95% CI, 52-79%). All of the studies had several limitations, such as small sample size, lack of comparison group, under-reporting of data and methods, and being observational studies. Adverse events (AEs) were transient and improved with temporary cessation of the drug and/or adjustment of the dose. No long-term AEs, including cancer or end organ damage were reported. Authors’ conclusion Hydroxyurea appears to be effective in the management of β-TM by decreasing the need for chronic blood transfusions completely or partially in a significant number of patients. It appears to be well tolerated and associated with mild and transient AEs. Patients with β-TM may benefit from a trial of hydroxyurea, though large RCTs assessing efficacy should be done to confirm the findings of this meta-analysis. Disclosures Off Label Use: Hydroxyurea for β-Thalassemia.

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