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Background and Objective: In longitudinal epidemiological studies consisting of a baseline stage and a follow-up stage, observations at the baseline stage may contain a countable proportion of negative responses. The time-to-event outcomes of those observations corresponding to negative responses at baseline can be denoted as zeros, which are excluded from standard survival analysis. Consequently, some important information on these subjects is therefore lost in the analysis. Furthermore, subjects are often clustered within hospitals, communities or health service centers, resulting in correlated observations. The framework of the two-part model has been developed and utilized widely to analyze semi-continuous data or count data with excess zeros, but its application to clustered time-to-event data with clumping at zero remains sparse., Methods: A two-part mixed-effects modeling approach was proposed. A logistic mixed-effects regression model was used in the first part to determine factors associated with the prevalence of the baseline event of interest. Parametric frailty models (including Weibull, exponential, log-logistic and log-normal) were used in the second part to assess associations between exposures and time-to-event outcomes. Correlated random effects were incorporated within the two regression models to accommodate the inherent correlation within each clustering unit and the correlation between the two parts. As an illustrative example, the method was applied to exclusive breastfeeding data from a community-based prospective cohort study in Nepal., Results: A significantly positive correlation between the baseline prevalence of exclusive breastfeeding and exclusive breastfeeding duration was confirmed (ρ = 0.67, P < 0.001). The correlated two-part model outperformed the independent two-part model (likelihood ratio test statistic = 8.6, df = 1, P = 0.003)., Conclusions: The proposed approach makes full use of all available information at baseline and during the follow-up, compared to the conventional survival analysis. In addition to breastfeeding studies, the method can be applied to other research areas where clustered time-to-event data with clumping at zero arise., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019. Published by Elsevier B.V.)

Background: Correlated breastfeeding duration data are very common in infant feeding research using cohort designs. Intracluster correlation within the same clustering group is expected and needs to be taken into account in statistical analysis; otherwise, the corresponding statistical inferences may be subject to an increased Type I error., Objectives: The aims of this study were to illustrate the necessity of adjusting for the intracluster correlation in correlated breastfeeding duration data analysis and to demonstrate different frailty modeling approaches., Methods: An introduction to shared frailty models was presented under the assumption of proportional hazards (PH). Then, two different approaches-the Cox frailty model (semiparametric approach) and the parametric frailty model (parametric approach)-were used to fit the data from a maternal cohort in Nepal as an illustrative example., Results: For the semiparametric approach, random effects denoting the variations in the hazard of breastfeeding cessation shared by mothers living in the 27 distinct communities were estimated and graphically presented. Compared with the conventional Cox model, Cox frailty model reduced the chance of Type I error occurring, providing a better model fit in the presence of correlated survival data. Among candidate parametric approaches, a Weibull PH model with a gamma frailty term was selected as an appropriate model fitting the breastfeeding data., Discussion: Shared frailty models can be used in other research areas in the presence of correlated time-to-event data. Model selection depends on the assumption of PH, the specification of the baseline hazard function, and also the study purpose.

Background: Mastitis is a painful problem experienced by breastfeeding women, especially in the first few weeks postpartum. There have been limited studies of the incidence of mastitis from traditionally breastfeeding societies in South Asia. This study investigated the incidence, determinants, and management of mastitis in the first month postpartum, as well as its association with breastfeeding outcomes at 4 and 6 months postpartum, in western Nepal., Subjects and Methods: Subjects were a subsample of 338 mothers participating in a larger prospective cohort study conducted in 2014 in western Nepal. Mothers were interviewed during the first month postpartum and again at 4 and 6 months to obtain information on breastfeeding practices. The association of mastitis and determinant variables was investigated using multivariable logistic regression, and the association with breastfeeding duration was examined using Kaplan-Meier estimation., Results: The incidence of mastitis was 8.0% (95% confidence interval, 5.1%, 10.8%) in the first month postpartum. Prelacteal feeding (adjusted odds ratio = 2.76; 95% confidence interval, 1.03, 7.40) and cesarean section (adjusted odds ratio = 3.52; 95% confidence interval, 1.09, 11.42) were associated with a higher likelihood of mastitis. Kaplan-Meier estimation showed no significant difference in the duration of exclusive breastfeeding among the mothers who experienced an episode of mastitis and those who did not., Conclusions: Roughly one in 10 (8.0%) women experienced mastitis in the first month postpartum, and there appeared to be little effect of mastitis on breastfeeding outcomes. Traditional breastfeeding practices should be encouraged, and the management of mastitis should be included as a part of lactation promotion., Competing Interests: Statement No competing financial interests exist.

Many deliveries in low income countries still take place at home and the newborns are often not weighed. This community-based study ascertained the incidence of low birthweight (LBW) and compared the birthweight between home- and facility-born neonates in central Nepal. A total of 701 pregnant women from the Kaski district were recruited and interviewed. Birthweights of newborns were measured by pan balance in health facility settings immediately after birth, or by local community health volunteers using colour-coded spring balance within 48 h of home birth. Household follow up of participants were undertaken less than 45 days after delivery to record the weight of their infants. Of the 639 postpartum women who took part in the follow up interview, information on birthweight was available from 605 singleton births. Among them, 65 (10.7 %) were born at home. Overall, the mean birthweight was 3,059 (SD 464) g and incidence of LBW was 16.5 % (95 % CI 13.5-19.5 %). However, the home-born infants reported significantly lower (p = 0.009) mean birthweight (2,920, SD 435 g) than their facility-born counterparts (3,078, SD 461 g). This difference in birthweight remained significant (p = 0.03) after adjustment for maternal and socio-demographic characteristics. Incidence of LBW in central Nepal was quite high. Home-born babies appeared to have lower birthweight and thus their inclusion could provide an accurate estimate of the LBW rate.

Objective: To determine the incidence of obstetric complications, the stillbirth rate, and the factors associated with cesarean delivery in central Nepal., Methods: A community-based prospective cohort study was undertaken in the Kaski district during 2011-2012. In total, 701 women who were at least 5 months pregnant were recruited and interviewed. Participants were followed-up and interviewed again within 45 days after delivery., Results: Of the 658 women who remained in the cohort after 43 were lost to follow-up, 12 (1.8%) had stillbirths. Cesareans accounted for 13.3% of the total deliveries. Age, urban residency, college-level education, and particularly presence of intrapartum symptoms significantly increased the likelihood of cesarean delivery. Prepartum, intrapartum, and postpartum symptoms were reported by 21.1%, 24.4%, and 10.2% of women, respectively. Common danger signs included prolonged labor, severe abdominal pain, swollen hand and body, and heavy bleeding., Conclusion: Obstetric complications and stillbirth rates were relatively high in central Nepal. Cesarean delivery appeared to meet obstetric need and was performed with medical indication, particularly after the onset of labor., (Copyright © 2013 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.)

Objective: to assess birth preparedness in expectant mothers and to evaluate its association with skilled attendance at birth in central Nepal., Design: a community-based prospective cohort study using structured questionnaires., Setting: Kaski district of Nepal., Participants: a total of 701 pregnant women of more than 5 months gestation were recruited and interviewed, followed by a second interview within 45 days of delivery., Measurements: outcome was skilled attendance at birth. Birth preparedness was measured by five indicators: identification of delivery place, identification of transport, identification of blood donor, money saving and antenatal care check-up., Findings: level of birth preparedness was high with 65% of the women reported preparing for at least 4 of the 5 arrangements. It appears that the more arrangements made, the more likely were the women to have skilled attendance at birth (OR=1.51, p<0.001). For those pregnant women who intended to save money, identified a delivery place or identified a potential blood donor, their likelihood of actual delivery at a health facility increased by two to three fold. However, making arrangements for transportation and antenatal care check-up were not significantly associated with skilled attendance at birth., Conclusions: intention to deliver in a health-care facility as measured by birth preparedness indicators was associated with actual skilled attendance at birth. Birth preparedness packages could increase the proportion of skilled attendance at birth in the pathway of meeting the Millennium Development Goal 5., (© 2013 Elsevier Ltd. All rights reserved.)