An observational study of missing data inquiry from randomized trial authors showed a poor response

SUMMARYVaccine effectiveness (VE) studies are subject to biases due to depletion of at-risk persons or of highly susceptible persons at different rates from different groups (depletion-of-susceptibles bias), a problem that can also lead to biased estimates of waning effectiveness, including spurious inference of waning when none exists. An alternative study design to identify waning is to study only vaccinated persons, and compare for each day the incidence in persons with earlier or later dates of vaccination. Prior studies suggested under what conditions this alternative would yield correct estimates of waning. Here we define the depletion-of-susceptibles process formally and show mathematically that for influenza vaccine waning studies, a randomized trial or corresponding observational study that compares incidence at a specific calendar time among individuals vaccinated at different times before the influenza season begins will not be vulnerable depletion-of-susceptibles bias in its inference of waning under the null hypothesis that none exists, and will – if waning does actually occur – underestimate the extent of waning. Such a design is thus robust in the sense that a finding of waning in that inference framework reflects actual waning of vaccine-induced immunity. We recommend such a design for future studies of waning, whether observational or randomized.

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Outcome of Pneumatic Balloon Dilatation in Achalasia Cardia

Journal of Advances in Internal Medicine ◽

10.3126/jaim.v10i1.37083 ◽

2021 ◽

Vol 10 (1) ◽

pp. 8-13

Author(s):

Shankar Baral ◽

Bidhan NIdhi Paudel ◽

Ajit Khanal ◽

Jiwan Thapa ◽

Bhuwneshwer Yadhav ◽

...

Keyword(s):

Observational Study ◽

Lower Esophageal Sphincter ◽

Poor Response ◽

Lower Esophageal Sphincter Pressure ◽

Pneumatic Dilatation ◽

Response To Treatment ◽

Sphincter Pressure ◽

Achalasia Cardia ◽

Type Iii ◽

Esophageal Sphincter

Background: Achalasia Cardia is a rare esophageal motility disorder. Among various treatment options, Pneumatic Dilatation (PD) is the most widely used and cost effective modality till date. This is the first observational study aiming to evaluate the short term response and complications of PD for Achalasia Cardia in Nepal. Methods: This prospective observational study was conducted between 28th Jan 2020 to 27th Jan 2021. It included 39 patients with Achalasia Cardia diagnosed by clinical presentation, esophagoscopy, barium esophagogram and high resolution manometry. Two patients of Type III achalasia were excluded from study. Thirty seven patients underwent pneumatic dilatation with 30 mm Rigiflex balloon (Boston Scientific, USA) for a duration of 1 minute. Response was assessed by Eckardts score at 3 and 6 months. Result: Among 39 cases (mean age= 39.03±15.017 years, 59% men), commonest was Type II Achalasia (71.8%) followed by Type I (23.1%) and Type III (5.1%). Dysphagia was present in all patients (100%), followed by weight loss (84.6%), regurgitation (79.5%) and chest pain (35.9%). Mean basal Eckardts score and Lower Esophageal Sphincter pressure of the study population was 7.81±1.24 and 24.40±6.83 respectively. Response to pneumatic dilatation was 89.2%. Eckardts score changed significantly from7.81±1.24 to 1.03±1.82 at 6 months (p<0.001). None of the patients had major complications. Younger age (23±6.377 years) had poor response to treatment, while predilatation Lower Esophageal Sphincter pressure, gender and type of achalasia did not affect the treatment outcome. Conclusion: PD is safe and effective treatment modality for Achalasia. Younger patients have poor response to treatment with Pneumatic Dilatation.

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Significant improvement of olfactory performance in sleep apnea patients after three months of nasal CPAP therapy – Observational study and randomized trial

PLoS ONE ◽

10.1371/journal.pone.0171087 ◽

2017 ◽

Vol 12 (2) ◽

pp. e0171087 ◽

Cited By ~ 4

Author(s):

Bettina Boerner ◽

Gabrielo M. Tini ◽

Patrick Fachinger ◽

Sereina M. Graber ◽

Sarosh Irani

Keyword(s):

Sleep Apnea ◽

Observational Study ◽

Randomized Trial ◽

Cpap Therapy ◽

Nasal Cpap

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Efficacy of intralesional bleomycin in treatment of lymphangiomas in children: an observational study

International Surgery Journal ◽

10.18203/2349-2902.isj20175902 ◽

2017 ◽

Vol 5 (1) ◽

pp. 238

Author(s):

Arun M. Ainippully ◽

Ranjit P. ◽

Arun Preeth V. ◽

Prathap S.

Keyword(s):

Observational Study ◽

Lymphatic Vessels ◽

Neck Region ◽

Poor Response ◽

Surgical Excision ◽

Ultrasound Measurement ◽

P Value ◽

Paediatric Surgery ◽

Excellent Response ◽

Pediatric Age Group

Background: Lymphangioma, a benign slow growing tumor of lymphatic vessels, common to the pediatric age group usually presents as swelling with cosmetic deformity. Commonly affecting the head and neck region it may present with compressive symptoms like airway obstruction or dysphagia. Previously surgical excision was the treatment of choice but it involves significant risks and so sclerotherapy has gained popularity. We conducted this prospective observational study to hava a quantitative analysis of the effect of intralesional bleomycin in reducing the size of lymphangiomas in children in our setup.Methods: This observational study was conducted in the paediatric surgery department between 2014 and 2016. A total of 34 children who presented with swellings which were diagnosed to be lymphangiomas based on clinical and sonological basis were included in the study and underwent intralesional bleomycin sclerotherapy. Details like dimensions of the lesion before and after the treatment, ultrasound measurement, residual size, characteristic of the cyst like presence or absence of septation, micro or macrocytic were recorded along with demographic details like age and sex. Outcome after 4 weeks was evaluated and classified into 3 groups as in excellent response, good response or poor response. Statistical analysis was done using R statistical software.Results: Of the 34 patients 59% were males. The median age was 18 months with inter-quartile range 4-36 months. 88% of patients had macrocystic lesions. 4 weeks after bleomycin sclerotherapy excellent response was seen in 23 (68%) of the patients, good in 8 (26%) and poor in 3 (9%) of the patients. There was statistically significant association between post procedure swelling, type of cysts and presence of septations and the number of sittings required to the outcome (p value <0.05).Conclusions: Present study shows that intralesional bleomycin sclerotherapy is very effective in the treatment of lymphangiomas in children, with macrocystic lesions showing a significantly better response.

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Randomized trial vs. observational study of acupuncture for migraine found that patient characteristics differed but outcomes were similar

Journal of Clinical Epidemiology ◽

10.1016/j.jclinepi.2006.06.014 ◽

2007 ◽

Vol 60 (3) ◽

pp. 280-287 ◽

Cited By ~ 12

Author(s):

Klaus Linde ◽

Andrea Streng ◽

Andrea Hoppe ◽

Wolfgang Weidenhammer ◽

Stefan Wagenpfeil ◽

...

Keyword(s):

Observational Study ◽

Randomized Trial ◽

Patient Characteristics

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Identifying patterns of item missing survey data using latent groups: an observational study

BMJ Open ◽

10.1136/bmjopen-2017-017284 ◽

2017 ◽

Vol 7 (10) ◽

pp. e017284 ◽

Cited By ~ 1

Author(s):

Adrian G Barnett ◽

Paul McElwee ◽

Andrea Nathan ◽

Nicola W Burton ◽

Gavin Turrell

Keyword(s):

Logistic Regression ◽

Missing Data ◽

Observational Study ◽

Latent Class ◽

Survey Design ◽

Latent Class Model ◽

Information Criterion ◽

Sleep Time ◽

Class Model ◽

Number Of Classes

ObjectivesTo examine whether respondents to a survey of health and physical activity and potential determinants could be grouped according to the questions they missed, known as ‘item missing’.DesignObservational study of longitudinal data.SettingResidents of Brisbane, Australia.Participants6901 people aged 40–65 years in 2007.Materials and methodsWe used a latent class model with a mixture of multinomial distributions and chose the number of classes using the Bayesian information criterion. We used logistic regression to examine if participants’ characteristics were associated with their modal latent class. We used logistic regression to examine whether the amount of item missing in a survey predicted wave missing in the following survey.ResultsFour per cent of participants missed almost one-fifth of the questions, and this group missed more questions in the middle of the survey. Eighty-three per cent of participants completed almost every question, but had a relatively high missing probability for a question on sleep time, a question which had an inconsistent presentation compared with the rest of the survey. Participants who completed almost every question were generally younger and more educated. Participants who completed more questions were less likely to miss the next longitudinal wave.ConclusionsExamining patterns in item missing data has improved our understanding of how missing data were generated and has informed future survey design to help reduce missing data.

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