Showing 4 results for Multilevel Analysis
M Gholami Fesharaki , A Kazemnejad , F Zayeri , M Rowzati, H Akbari,
Volume 10, Issue 4 (3-2015)
Abstract
Background and Objectives : Previous studies have reported contradictory results regarding the association of Shift Work (SW) and Blood Cholesterol (BC). In this paper, we studied the relationship between SW and BC.
Methods: The data of this historical cohort study was extracted from annual observations of the workers of Esfahan’s Mobarakeh Steel Company selected through cluster random sampling between 1996 and 2011. In this research, we assessed the effect of SW on BC with controlling BMI, age, work experience, marital status, smoking, and educational status.
Results : Five hundered and seventy four male workers participated in this study with a mean (SD) age of 41.89 (7.51) and mean (SD) work experience of 16.75 (7.16) years. In this study, after controlling confounding factors, we found no significant relationship between SW and BC.
Conclusion: Because our study showed no relationship between SW and BC, we can state that this relationship does not exist with more certainty.
M Amini, A Kazemnejad, F Zayeri , M Gholami Fesharaki,
Volume 13, Issue 4 (3-2018)
Abstract
Background and Objectives: Shift work could threaten health in the long term. The present research aimed to assess the association between shift work and body mass index (BMI) using the multilevel (hierarchical) model during a particular period of time.
Methods: The data of this longitudinal study were collected from a sample of Esfahan’s Mobarakeh steel and Polyacryl companies personnel during 2008 to 2011. Shift work schedule included day work and rotational shift work. The multilevel regression model was utilized for analysing the data and assessing the effect of shift work on BMI by controlling confounding variables including marital status, work expectation, age, company, and educational level.
Results: In this study, of 1368 workers, 42.3% (n=578) and 57.7% (n=790) were day workers and rotating shift workers, respectively. The mean (±SD) age of the day workers and rotating shift workers was 33.07 (±8.66) years and 33.31 (±8.70) years, respectively. After adjusting for confounding variables in a two-level hierarchical model, the association between shift work and BMI was not statistically significant (P=0.837). About 90% of total variation was related to personnel.
Conclusion: According to the results of the present study, no statistically significant relationship was found between shift work schedule and BMI. Thus, other similar studies with a longer follow up period (more than four years) and controlling more confounder factors are necessary to evaluate the relationship between shift work and BMI more accurately.
N Rabiei, M Gholami Fesharaki , M Rowzati,
Volume 14, Issue 3 (12-2018)
Abstract
Background and Objectives: The Cox model is one of the methods used in survival data; however, the use of hierarchical data, such as the data of this study, violates the assumption of independence, the the Cox model cannot be used assuming independence of observations. One of the important methods for analyzing survival hierarchy data is the use of the multilevel Cox model. In this method, in addition to modeling the response variable, regression coefficients are also modeled and the measurement error resulting from the lack of data independence is reduced. The present study used a multilevel Cox model to investigate the effect of the retention of antihypertensive drugs in people with hypertension.
Methods: This longitudinal survival study was conducted in 346 workers with hypertension in Mobarakeh Steel Company in Isfahan. During the years 1390-1394, when the staff attended the health center in the factory, they were treated with six drugs, including captopril, losartan, atenolol, propranolol, amlodipine, and hydrochlorothiazide. In order to examine the relationship of the retention of drugs with job experience, body mass index, and drug history, a two-level Cox model was used as h_ij (t)=h_0 (t)exp(α_g+x_ij β_j), where i and j is the first and second level units, respectively.
Results: During five years, the findings of model fitting showed the effect of body mass index (P = 0.019), atenolol (P=0.046), and amlodipine (P=0.021) in a single form, and the effect of losartan-amlodipine ¬(P=0.042) and atenolol-hydrochlorothiazide (P = 0.003) in a combination form were significant.
Conclusion: Based on the study results, the most effective drugs for hypertension control are amlodipine monotherapy, amlodipine-losartan combination therapy, and atenolol monotherapy, respectively.
Fereshteh Eidy, Hoosein Fallahzadeh, Rahman Panahi, Jamshid Jamali,
Volume 18, Issue 3 (12-2022)
Abstract
Background and Objectives: Today, overweight and obesity are among the significant challenges in the world. They can have adverse effects on quality of life. Quality of life is determined by social and physical environment. The present study investigated the construct validity of the Persian version of the Impact of Weight on Quality of Life (IWQOL-lite) questionnaire using multilevel confirmatory factor analysis.
Methods: The present study was conducted on 310 people over 18 years old living in Yazd city. The data were analyzed using m-plus6.2 software.
Results: The mean age of the participants in this study was 33.97± 4.70 years. Sixty percent (N=183) of subjects were male. The indices of the one-level model were more appropriate than those of the two-level model, and the one-level confirmatory factor analysis model had a good fitting to the data (CLI: 0.98, TLI: 0.98, RMSEA: 0.038).
Conclusion: The results of this study indicated the need for more effectiveness of urban areas on quality of life. The one-level confirmatory factor analysis model confirmed the construct validity of the IWQOL-lite questionnaire. This questionnaire can be used in the Iranian population.
