Job Stress and Risk of Menstrual Duration Disorder in Female Civilian Flight Attendants in Indonesia

Background: Menstrual duration disorder may cause impaired work performance. The research objectivewas to identify risk factors related to menstrual duration disorder in female flight attendants.Methods: A cross-sectional study with convenient sampling was conducted on civilian female flightattendants age 19–50 years who underwent routine medical examination at Civil Aviation Medical Centerand Garuda Sentra Medika, Jakarta on May 18-29 2015. Menstrual duration disorder is menstruation morethan 8 days and/or shorter than usual perid (3-5 days). Stress was identified by usingcriteria of NationalInstitute for Occupational Safety and Health Generic Job Stress Questionnaire Mental Demands FormNumber 11. Relative risk was analyzed usng Cox regression.Results: Among 521 female civilian flight attendants, 393 were willing to participate in this study. Nineteensubjects were excluded, leaving 374 subjects for this analysis, and 35.8% of subjects had menstrualduration disorder. Job stress, flight type and age were dominant risk factors for menstrual duration disorder.Subjects with job stress and long haul flight within three months had higher risk for having menstrualduration disorder by 58% [adjusted relative risk (RRa) = 1.58; confidence interval (CI) = 0.96-2.62; P =0.071] and 69% (RRa = 1.69; CI = 1.17-2.43) respectively. Those between aged 30-39 years had 50% hadless risk of having menstrual duration disorder (RRa=0.50; 95% CI = 0.22-1.02; P = 0.057).Conclusion: Female civilian flight attendants with job stress, long haul flight within three months and youngerage had higher risk to be menstrual duration disorder. (Health Science Journal of Indonesia 2015;6:87-91)

Female flight attendant is one of the profession that requires optimal health in order to maintain the safety of flight. 1 Female flight attendants often encounters health problems due to the environment. The problem, among other others, on reproductive disorders such as menstrual duration disorder. This problem may encounter the performance the female flight attendants in doing their job, which could compromise the flight safety. 2 Previous studies showed that several risk factors (age, habits, job stress, occupational, flight hours) related to menstrual duration disorder among flight attendants. 3 Female flight attendants have higher risk for having menstrual disorder compared to other non-flight attendant females and female ground crews. 4 Furthermore, female flight attendants have more job stress than non-flight attendants. 2 The job stress, among others, influences menstrual duration disorder in female civilian flight attendants. 5 In Indonesia, the study of several risk factors related to menstrual duration disorder is still rare. The study aimed to identify job stress and several other risk factors related to menstrual duration disorder among female flight attendants.

METHODS
The subjects of this purposively cross-sectional study consisted of female civilian flight attendants age 19-50 years who conducted routine medical examinations in Indonesian Aviation Medical Center in Jakarta and Garuda Sentra Medika in May 18-29, 2015.
Menstrual duration disorder defined as duration of menstruation more than 8 days and/or shorter than usual period (3-5 days).
Job stress was measured using the National Institute for Occupational Safety and Health (NIOSH) Generic Job Stress Questionnaire Mental Demands Form Number 11. The questionnaire has good validity and reliability (interval consistency -Cronbach's alpha 0.61). 6 The questionnaire consisted of 5 questions: (1) My job requires a great deal of concentration; (2) My job requires me to remember many different things; The answer in the form of a Likert scale with four choices: strongly agree, slightly agree, slightly disagree dan strongly disagree. Each answer was given a score of 1-4 by the researchers according to the female flight attendant answers.
Number 1 for the lowest score and number 4 for the highest score.
The score assessment inverted to question numbers 1-3, and then carried out a summation of the whole score. The lowest score at 5 and a highest of 20. The higher the score, the more likely a flight attendant job stress.
For this analysis we used the cut-off point for job stress that identified based on Receiver Operating Characteristics Curve (ROC) analysis. The results are: 0 =without job stres (total score 12 or less 12; 1 = = with job stress (total score 13 or more) The demographic, occupation, habit characteristics, job stress and menstrual duration disorder data were collected based on interview using a questionnaire for this study. Height and weight data was obtained from the medical records.
For this study, occupational risk factors were categorized: the most frequent flight type since last week, last three months, and last year (short haul was 2 hours or less, intermediate haul was 2 -6 hours, and long haul was 6 hours or more); rating type (Boeing, Airbus, ATR and others); total flight hours within three months (21-225 hours and 226-500 hours).
Smoking was categorized into 3 categories: never smoke, was smoking and currently smoking.
Flight type categorized as 1 = short haul; 2 =intermediate haul; and 3 = lo ng haul. Short haul if one flight sector less than 2 hours; intermediate haul when the flight for one sector is 2 to 6 hours; long haul for the flight in one sector more than 6 hours.
The analysis in this study used Cox regression with constant time. 7 Data were analyzed using STATA version 9.
Ethical approval was obtained from the Health Research Ethics Committee of the Faculty of Medicine, Universitas Indonesia, Jakarta. This study was conducted upon approval the Chief of Civil Aviation Medical Center, Directorate General of Civil Aviation, Jakarta and Chief of Garuda Sentra Medika.

RESULTS
Among the 521 female civilian flight attendants who underwent routine medical examination, 393 subjects agreed to join the study. We excluded 19 subjects who ever had menstrual duration disorder before being employed. Therefore, leaving 374 subjects included for this analysis. None of the included subjects was obese Table 1 showed that 35.8% (134/374) subjects had menstrual duration disorder. Subjects with or without menstrual duration disorder were similarly distributed in terms of body mass index and smoking habit, total flight hours within three months, rating type and flight type since last week and last year. In term of long haul flight within three months, those who long haul flight within three months compared to short haul flight had 69% higher risk for having menstrual duration disorder (RRa=1.69; P = 0.004).

DISCUSSION
This study had several limitations, among others, this study was conducted among limited and with purposive s elected civilian flight attendants. The selected samples did not represent the general civilian flight attendants. Furthermore, there were some misinterpretation by the subjects while answering the questions listed in the questionnaire. Even though, we explained the questionnaire before the interview.
In this study, we noted that female civilian flight attendants with job stress had higher risk for having menstrual duration disorder. This result is similar with the previous study of menstrual duration disorder in female civilian flight attendants in Indonesia. 8 Job stress in female civilian flight attendants stimulates the secretion of CRH (corticotropin releasing hormone) and will suppress GnRH (gonadotropinreleasing hormone) in hypothalamus that releases (adrenocorticotropic hormone (ACTH) which stimulates the production of glucocorticoid hormones. Glucocorticoid hormones (cortisol, adrenaline and androgen) inhibits GnRH, follicle stimulating hormone (FSH) -luteinizing hormone (LH) and ovary, causing follicular atresia, thus lowering the estrogen level and will result in menstrual disorder. 9 Furthermore, in this study we also noted that female civilian flight attendants with long haul flight within three months compared to short haul flight had 69% statistically significant higher risk of having menstrual duration disorder. This result was different with a previous study that reported that female flight attendants who had 8 hours or more compared to those who had less than 8 hours flight had more risk (but not statistically significant) had menstrual disorder. 2 The difference might be due to the grouping of hours, which is more than 6 hours in this study, and limited to the last three months.
Menstrual disorder related to sleep cycle may be disturbed by jet lag caused by long haul flight or shift lag in the working environment. This will cause hypothalamo-pituitary-ovarian axis dysfunction, which are also related to stress and the secretion of LH. Sleep directly inhibits LH secretion, thus lowering the LH level on the early follicular phase and affects the menstrual pattern. 10 Our study noted that compared with the female civilian flight attendants aged 19-24 years, female civilian flight attendants aged 30-39 years had 50% less risk for having menstrual duration disorder.
The adaptation process within working environment between 30-39 years subjects might be better than the 19-24 years old. 11 In addition, aging process that starts at 40 years affects the ovary's ability to react to the stimulation of gonadotropin hormones. 2 In conclusion, female civilian flight attendants with job stress, long haul flight within three months and compared with the female civilian flight attendants aged 19-24 years, those who had age 30-39 years had 50% less risk for having menstrual duration disorder.