Nevin Manimala

Stat Med. 2026 Feb;45(3-5):e70351. doi: 10.1002/sim.70351.

ABSTRACT

Mediation analysis aims to identify and estimate the effect of an exposure on an outcome that is mediated through one or more intermediate variables. In the presence of multiple intermediate variables, two pertinent methodological questions arise: estimating mediated effects when mediators are correlated, and performing high-dimensional mediation analyses when the number of mediators exceeds the sample size. This paper presents a two-step procedure for high-dimensional mediation analyses. The first step selects a reduced number of candidate mediators using an ad-hoc lasso penalty. The second step applies a procedure we previously developed to estimate the mediated effects, accounting for the correlation structure among the retained candidate mediators. We compare the performance of the proposed two-step procedure with state-of-the-art methods using simulated data. Additionally, we demonstrate its practical application by estimating the causal role of DNA methylation (DNAm) in the pathway between smoking and rheumatoid arthritis (RA) using real data.

PMID:41646011 | DOI:10.1002/sim.70351

J Vasc Access. 2026 Feb 6:11297298261415955. doi: 10.1177/11297298261415955. Online ahead of print.

ABSTRACT

BACKGROUND: Arterial blood gas (ABG) analysis is essential in the emergency department (ED) for the rapid assessment of acid-base status, oxygenation, and metabolic disturbances in critically ill patients. The distal forearm (DF) is the conventional site for radial arterial puncture. Recent studies in interventional cardiology have explored the anatomical snuffbox (ASB) approach as an alternative vascular access site; however, its utility for ABG sampling in the ED remains unclear.

METHODS: In this single-center, randomized controlled non-inferiority trial conducted from May 2022 to October 2023, 356 adult patients requiring ABG analysis in the ED were randomized in a 1:1 ratio to undergo sampling via either the ASB or DF approach. Eligible patients had a palpable radial pulse at both access sites, while those with hypotension, local site abnormalities, or a positive Allen’s test were excluded. The primary outcome was the first-pass success rate; secondary outcomes included the number of attempts, failure rates (defined as failure to obtain a sample after three attempts), and procedure-related complications observed during a 12-h ED stay.

RESULTS: The DF approach demonstrated a significantly higher first-pass success rate (74.7%) compared with the ASB approach (60.7%; p = 0.006). The failure rate was lower in the DF group (5.1%) relative to the ASB group (21.3%; p < 0.001). Although minor complications such as hematoma, arterial spasm, and bleeding were noted in both groups, there were no statistically significant differences in overall complication rates.

CONCLUSIONS: Although the anatomical snuffbox (ASB) approach has been proposed as an alternative access site based on potential benefits in other procedural settings, this trial found that it did not meet non-inferiority compared with the conventional distal forearm (DF) method for ABG sampling in the ED. Given the higher failure rate with the ASB approach, the DF method remains the preferred sampling site in this setting.

TRIAL REGISTRATION: The Clinical Trials Registry – India (CTRI/2022/07/044216).

PMID:41646008 | DOI:10.1177/11297298261415955

Natl Med J India. 2026 Jan-Feb;39(1):23-29. doi: 10.25259/NMJI_295_2023.

ABSTRACT

Background There is minimal literature on the spectrum and long-term outcomes of acute kidney injury (AKI) from tropical countries. Methods Patients with AKI without underlying chronic kidney disease (CKD), were recruited from March 2017 to December 2018 to assess their outcomes. Survivors were followed for a year post-discharge. A linear model with fixed effects was created to compare the estimated glomerular filtration rate (eGFR) trajectories of patients with and without CKD at the end of follow-up. Results A total of 529 patients with AKI were recruited, of which 288 (54.4%) were hospital-acquired AKI. Infections and sepsis were the most common aetiologies for community-acquired AKI and hospital-acquired AKI. The overall mortality rate was 42.9% (n=227). The ICU stay (HR 1.78; 95% CI 1.08-2.93), mechanical ventilation (HR 1.98; 95% CI 1.09-3.54), and the requirement for inotropic support (HR 2.36; 95% CI 1.65-3.39) were independent risk factors of in-hospital mortality. Among 156 subjects with long-term follow-up, 70 (44.9%) developed CKD after a median follow-up of 12 months. Age (p<0.001) and hospital-acquired AKI (p=0.014) were significant predictors, whereas ICU stay and comorbid conditions did not influence the GFR trajectories. CKD patients showed a lower eGFR from the first follow-up (p<0.001). Conclusions AKI is associated with significant mortality. Even after an apparent recovery, around half the survivors progress to CKD at the end of 1 year.

PMID:41645992 | DOI:10.25259/NMJI_295_2023

Natl Med J India. 2026 Jan-Feb;39(1):19-22. doi: 10.25259/NMJI_222_2023.

ABSTRACT

Background Long-term Covid-19 symptoms have the potential to negatively impact health and quality of life. We evaluated the incidence and predictors of long Covid-19 among hospitalized patients. Methods We prospectively collected clinical data of 393 patients diagnosed as Covid-19 positive and admitted to our hospital. At 1-year follow-up, all vital parameters and laboratory investigations were recorded. A multiple logistic regression model was used to determine predictors of long Covid-19. Results Long Covid-19 was found in 34.4% of patients at 1-year follow-up. Most commonly reported symptoms were joint pain (40%), fatigue (33%), and dyspnoea (22.9%). Severity of disease at the time of admission (1.5; 95% Confidence Interval [CI] 1.09-2.2; p=0.01), high body-mass index (BMI) (1.1; 95% CI 1.03-1.13; p=0.003) and increased age (1.02; 95% CI 1.00-1.04; p=0.02) were independent predictors of long Covid-19 on follow-up. Conclusion Almost one-third of patients were diagnosed with long Covid-19 at 1-year follow-up. Severity of disease at the time of admission, increased BMI, and increased age were independent predictors of long Covid-19.

PMID:41645987 | DOI:10.25259/NMJI_222_2023

Natl Med J India. 2025 Nov-Dec;38(6):339-343. doi: 10.25259/NMJI_364_2023.

ABSTRACT

Background Integration of smart mobile devices (SMD) like smartphones and digital tablets into medical practice continues to be hindered despite the benefits of access to guidelines at the point of care and patient safety. The barriers include administrator attitudes, perceptions about how patients would receive it, shyness about accessing it in the presence of coworkers, and perceived attrition in medical education. We aimed to understand the perceptions of doctors, medical students, and patients about the use of SMDs in patient care areas. Methods A cross-sectional survey of doctors, medical students, and patients across multiple states in India was conducted. Data were collected using a validated questionnaire after ethical clearance and participant consent. A sample size of 385 was estimated for each group (95% confidence interval, alpha error 0.5, power 80%). Results 406 doctors, 425 medical students, and 418 patients responded to the survey. 92% doctors, 96% medical students, and 57% patients owned an SMD. 81% doctors had used an SMD for patient care, with a little over 50% having used it in front of their juniors, and only 34% approved the use in patient contact areas. 99% medical students used SMD for studying; 93% advocated it to their juniors for learning, but only 68% used it in front of their juniors, and 29% in front of their patients. About 90% patients were ready for doctors to use SMDs in front of them, with over 75% agreeing that SMD use will lead to better and safer care. Conclusions SMDs are widely used in the patient care area and for medical education. Some perceived barriers such as patient perceptions about doctors require behavioural change and acceptance of changing times.

PMID:41645985 | DOI:10.25259/NMJI_364_2023

Natl Med J India. 2025 Nov-Dec;38(6):326-331. doi: 10.25259/NMJI_988_2022.

ABSTRACT

Background One of the most important indicators of mental health in old age is life satisfaction. We aimed at verifying the psychometric properties of the Life Satisfaction Index-A (LSIA), used to evaluate life satisfaction and well-being, among older Iranians. Methods The forward-backward procedure was used for translating the English version of the LSIA into Persian. Thereafter, face and content validity were done by 15 specialists. Confirmatory factor analysis (CFA) was done for construct validity. Reliability was evaluated by using the Cronbach’s alpha method. Statistical analysis was performed using Mplus 7.4. p<0.05 was considered statistically significant. Results In the face validity, more than 90% of all questions had an impact score above 1.5, content validity ratio (CVR) >0.6, and content validity index (CVI) >0.8. CFA showed that the first-level factors ‘resolution and fortitude’, ‘Zest’ and ‘congruence between desired and achieved goals in life’ explain the first factor of the second level which is ‘the perception of reality’, and the first level factors ‘positive self-concept’ and ‘mood tone’ explain the second factor of the second level which is ‘mental perception’. The proposed structural model showed acceptable to the data and Cronbach’s alpha for the LSIA’s dimensions ranged between 0.89 and 0.95. Conclusion The findings suggest that the LSIA appears to be an appropriate instrument for older adults in Iran, but it needs further validation to explore different sub-cultural aspects in the older Iranian population.

PMID:41645981 | DOI:10.25259/NMJI_988_2022

Natl Med J India. 2025 Nov-Dec;38(6):344-349. doi: 10.25259/NMJI_726_2022.

ABSTRACT

Background Transmission of the delta variant resulted in a surge of SARS-CoV-2 cases in New Delhi, India, during the early half of the year 2021. Healthcare workers (HCWs) received vaccines on priority for the prevention of infection. We estimated the effectiveness of the BBV152 vaccine among HCWs against SARS-CoV-2 infection, hospitalization, or death. Methods This retrospective cohort study was done at a multi-speciality tertiary care public-funded hospital in New Delhi, India. 12 237 HCWs participated in the study. The intervention was the BBV152 whole virion inactivated vaccine (Covaxin, Bharat Biotech Limited, Hyderabad, administered two doses four weeks apart). The outcome measures were vaccine effectiveness against any SARS-CoV-2 infection, symptomatic infection, or hospitalization or death. Results The mean (SD) age of HCWs was 36 (11) years, 66% were men, and 16% had comorbid conditions. After adjusting for potential covariates-age, sex, health worker type category, body mass index, and comorbid conditions, the vaccine effectiveness (95% confidence interval) in fully vaccinated HCWs and >14 days after receipt of the second dose was 44% (37 to 51, p<0.001) against sympto-matic infection, hospitalization or death due to SARS-CoV-2, and 61% (37 to 76, p<0.001) against hospitalization or death, respectively. The partial dose was not effective. Conclusion The BBV152 vaccine, with complete two doses, offered a modest response to SARS-CoV-2 infection in real-life situations against a backdrop of high delta variant community transmission.

PMID:41645980 | DOI:10.25259/NMJI_726_2022

Natl Med J India. 2025 Nov-Dec;38(6):332-338. doi: 10.25259/NMJI_824_2022.

ABSTRACT

Background In the Indian context, there is no recent data on substance use among school students. We report on the pattern of substance use and associated factors among school students in a cross-sectional nationwide survey conducted in 10 cities of India. Methods From each city, data from 200 students each from three schools (urban-government, urban-private, rural school) were collected. Within each school, a section from each grade (VIII, IX, and XI/XII) was randomly selected. Finally, 5920 students (boys 52.4%, mean [SD] age 14.7 [1.6] years) self-administered the questionnaire in the classroom setting. Results There were 15.1% students who reported lifetime, 10.3% past year, and 7.2% past month use of any substance, including tobacco, with most being used occasionally. Substances used in the past year were tobacco (4%), alcohol (3.8%), opioids (2.8%), cannabis (2%), inhalants (1.9%), and sedatives (0.6%). Substance use was significantly higher among boys than girls and higher with increasing grades. Past year users had significantly high/very high total difficulties score on the Strengths and Difficulties Questionnaire (15.0 [5.1]) compared to non-users (13.4 [5.7]; p<0.001). There was a significant difference between substance users and non-users in the subscales conduct problem, hyper-activity, emotional problems, and in the impact score (p<0.001). Past year users compared to non-users reported higher ‘substance use (any)’ by family members (p<0.001) and peers (p<0.001). Conclusions A substantial proportion of school students reported using psychoactive substances, mostly for occasional use. School-based prevention efforts are required on a wide scale in the country. We recommend early identification and intervention for substance use in school settings.

PMID:41645979 | DOI:10.25259/NMJI_824_2022

Natl Med J India. 2025 Nov-Dec;38(6):365-368. doi: 10.25259/NMJI_398_2024.

ABSTRACT

Background The doctor-patient relationship is an important component of modern medicine. It is essenstial to respect the patient’s views while also conveying the appropriate treatment protocols to them. We aimed to determine the characteristics that the general public in India considers important in a ‘Good doctor’ who would treat them or a member of their family. Methods We did a cross-sectional questionnaire-based study including 402 participants. The questionnaire consisted of 21 physicians’ characteristics, with 7 characteristics in each of 3 domains: professional expertise, humanism, and autonomy. Participants were asked to select 4 qualities they valued most. Descriptive statistics were calculated and summarized. Categorical variables were analysed using the Chi-square test. The level of significance was set at 5%. Results The majority of patients (273) wanted their doctor to provide a clear explanation of their disease, while 218 patients wanted their doctor to be honest about their illness. The most commonly preferred domain was autonomy (84.3%), 75.1% chose humanism as the preferred characteristic while 74.6% favoured professional expertise. Conclusion The growing exposure to health education has changed people’s perceptions from ‘only doctors decision’ to ‘shared decision-making’. Open and transparent communication with patients reinforces trust in the doctor- patient relationship and must go hand in hand with humanism and professional competence.

PMID:41645971 | DOI:10.25259/NMJI_398_2024

Natl Med J India. 2025 Sep-Oct;38(5):268-274. doi: 10.25259/NMJI_878_2023.

ABSTRACT

Background We aimed to evaluate the efficacy and safety of anticoagulant therapy, especially direct oral anticoagulant (DOAC) therapy, for primary prevention of venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism (PE), in non-bedridden cancer patients undergoing chemotherapy. Methods English and Chinese literature published from the inception of the databases up to December 2022 was extracted from five databases: PubMed, Embase, MEDLINE, Wanfang Medical and CNKI. Statistical analysis was done using Stata/SE 16.0 software. Results Eight randomized controlled trials were included in this meta-analysis. The results showed that DOACs were effective in preventing symptomatic PE in cancer patients (Log risk ratio [RR]=-0.89, 95% confidence interval [CI]: -1.73, -0.05). Moreover, compared to the control group, DOACs did not increase the risk of major bleeding (Log RR 0.55, 95% CI -0.20, 1.30). Conclusion The meta-analysis indicates that in cancer patients, DOACs have a significant effect on the prevention of PE, with good safety profile and no increased risk of major bleeding.

PMID:41645951 | DOI:10.25259/NMJI_878_2023