Open Access

Changes in the SF-8 scores among healthy non-smoking school teachers after the enforcement of a smoke-free school policy: a comparison by passive smoke status

  • Kosuke Kiyohara1,
  • Yuri Itani2,
  • Takashi Kawamura1,
  • Yoshitaka Matsumoto2 and
  • Yuko Takahashi3Email author
Health and Quality of Life Outcomes20108:44

https://doi.org/10.1186/1477-7525-8-44

Received: 7 September 2009

Accepted: 28 April 2010

Published: 28 April 2010

Abstract

Background

The effects of the enforcement of a smoke-free workplace policy on health-related quality of life (HRQOL) among a healthy population are poorly understood. The present study was undertaken to examine the effects of the enforcement of a smoke-free school policy on HRQOL among healthy non-smoking schoolteachers with respect to their exposure to passive smoke.

Methods

Two self-reported questionnaire surveys were conducted, the first before and the second after the enforcement of a total smoke-free public school policy in Nara City. A total of 1534 teachers were invited from 62 schools, and their HRQOL was assessed using six domains extracted from the Medical Outcomes Survey Short Form-8 questionnaire (SF-8): general health perception (GH), role functioning-physical (RP), vitality (VT), social functioning (SF), mental health (MH), and role functioning-emotional (RE). The participants were divided into two groups according to their exposure to environmental tobacco smoke (ETS) at baseline: participants not exposed to ETS at school (non-smokers), and participants exposed to ETS at school (passive smokers). Changes in each SF-8 score were evaluated using paired t-tests for each group, and their inter-group differences were evaluated using multiple linear regression analyses adjusted for sex, age, school type, managerial position, and attitude towards a smoke-free policy.

Results

After ineligible subjects were excluded, 689 teachers were included in the analyses. The number of non-smokers and passive smokers was 447 and 242, respectively. Significant changes in SF-8 scores were observed for MH (0.9; 95% confidence interval [CI], 0.2-1.5) and RE (0.7; 95% CI, 0.0-1.3) in non-smokers, and GH (2.2; 95% CI, 1.2-3.1), VT (1.8; 95% CI, 0.9-2.7), SF (2.7; 95% CI, 1.6-3.8), MH (2.0; 95% CI, 1.0-2.9), and RE (2.0; 95% CI, 1.2-2.8) in passive smokers. In the multiple linear regression analyses, the net changes in the category scores of GH (1.8; 95% CI, 0.7-2.9), VT (1.4, 95% CI, 0.3-2.5), SF (2.5; 95% CI, 1.1-3.9), MH (1.2; 95% CI, 0.1-2.4) and RE (1.6; 95% CI, 0.5-2.7) in passive smokers significantly exceeded those in non-smokers.

Conclusions

A smoke-free school policy would improve the HRQOL of healthy non-smoking teachers who are exposed to ETS.

Background

Exposure to environmental tobacco smoke (ETS) is one of the major worldwide public health issues. Secondhand smoke is well known to definitely cause reproductive, developmental, respiratory, cardiovascular, and neoplastic diseases, as indicated in the U.S. Surgeon General's report published in 2006 [1], although its individual effects are difficult to quantify. In addition, exposure to ETS has been also reported to reduce the health-related quality of life (HRQOL) of never smokers even in the general population [2] as well as of patients with asthma [3] or chronic obstructive pulmonary diseases (COPD) [4].

One possible solution for the elimination of health hazards from ETS is to make public places smoke-free. Previous studies suggested that smoke-free workplace policies could contribute to the reduction in respiratory symptoms of workers [5, 6] and heart disease morbidity/mortality [7, 8]. In addition, one study also suggested that disease-specific quality of life among non-smoking asthmatic bar workers would significantly improve after the implementation of smoke-free legislation [9].

However, the effects of smoke-free legislation on HRQOL of the healthy population are still unknown. Odor annoyance and ocular/nasal irritation are well-known acute symptoms of secondhand smoke [10, 11], and some acute respiratory symptoms, including coughing, wheezing, chest tightness, and breathing difficulty, might occur among healthy persons exposed to ETS [1215]. As the U.S. Surgeon General's report mentioned, these respiratory and sensory symptoms may potentially deteriorate HRQOL [1]. Therefore, eliminating or reducing secondhand smoke would contribute to the improvement of HRQOL even for healthy persons.

The Health Promotion Law of Japan, which came into force in 2002, put the managers of facilities of a public nature, including restaurants, cafes, public transportation, schools, and offices, under an obligation to control secondhand smoke. In accordance with this legislation, the Nara City government implemented a smoke-free school policy in all public schools in April 2007. Taking this opportunity, the researchers examined how the HRQOL of subjectively healthy schoolteachers changed. The goal of the present study was to investigate the effects of the smoke-free school policy on HRQOL among healthy non-smoking schoolteachers with respect to their exposure to passive smoke.

Methods

Survey and participants

Two self-reported questionnaire surveys were conducted in January 2007 and September 2007, the first three months before and the second five months after the enforcement of the total smoke-free public school policy in Nara City, respectively. The questionnaire forms were sent to 1748 teachers affiliated with 70 public elementary, junior high, and senior high schools in Nara City for each survey. Since eight out of 70 schools had already adopted the smoke-free school policy of their own accord before the first survey, the 214 teachers assigned to these schools were excluded, and the remaining 1534 were enrolled in the study. Among the latter group, participants who answered both the baseline and follow-up questionnaires, had no missing values in the required questionnaire items, did not smoke at baseline, and did not have definite/suspected diseases at baseline, were eligible for the following analyses.

Data collection

HRQOL was assessed by the Medical Outcomes Survey Short Form-8 questionnaire (SF-8) [16]. SF-8 consists of eight items, each representing one health profile dimension: general health perception (GH), physical functioning (PF), role functioning-physical (RP), bodily pain (BP), vitality (VT), social functioning (SF), mental health (MH), and role functioning-emotional (RE). Each item of the SF-8 is assessed using a 5- or 6-point Likert scale, and is standardized according to the scoring system, in which 50 points represents the national standard value for health and functioning. The Japanese version of the SF-8 meets the standard criteria for content and for construct and criterion validity, based on the national survey covering 1,000 Japanese general citizens in 2002 [16]. We chose six out of the eight items of SF-8: GH, RP, VT, SF, MH, and RE for the analyses. In addition to HRQOL, sex, age, school type, managerial position, current smoking status, experience of secondhand smoke at school during the past month, and attitude towards the smoke-free school policy were also examined in the self-report questionnaire. Attitude towards the smoke-free school policy was examined using a 5-point Likert scale (very positive, rather positive, equivocal, rather negative, and very negative).

Statistical methods

The participants were divided into two groups according to their experience of secondhand smoke at baseline: participants not exposed to ETS (non-smokers) and participants exposed to ETS (passive smokers).

Differences in the baseline characteristics between the groups were evaluated using chi-square test, and those in the baseline scores for the SF-8 between the groups were evaluated using Student's t-test. Changes in each score between before and after the enforcement of the smoke-free policy were evaluated using paired t-test in both groups. The level of significance was set at 5%. In addition, the differences of the net changes in each category score between the groups were evaluated using multiple linear regression analysis to calculate partial regression coefficients and their 95% confidence intervals (CIs), adjusted for sex, age, school type, managerial position, and attitude towards the smoke-free school policy. All analyses were conducted with the SPSS v.15.0 J for Windows statistical software (SPSS Inc., Chicago, IL).

Ethics

Answering the questionnaires was voluntary, and all the participants were identified by research-specific numbers after removing personal identifiers. This study protocol was approved by the ethics committee of Nara Women's University.

Results

Baseline characteristics of the participants

Figure 1 shows the flowchart of the participants included in the present study. Out of 1534 enrollees, 1122 completed the baseline questionnaire without data missing. Excluding teachers who smoked at baseline, had definite/suspected diseases at baseline, did not answer the follow-up questionnaire, and had missing data in the follow-up survey, the remaining 689 were eligible for the analyses. Compared with the eligible participants (n = 689), teachers who did not answer the follow-up questionnaire or had missing data in the SF-8 at follow-up (n = 234) were somewhat more likely to be male (106 of 234 [45%] vs 257 of 689 [37%]; p = 0.030) and had a less positive attitude towards the smoke-free school policy (173 of 234 [74%] vs 555 of 689 [81%]; p = 0.032).
Figure 1

Flowchart of the study participants.

After the enforcement of the smoke-free policy, 16 (14%) of the 111 smoking teachers completing the follow-up survey had quit smoking successfully.

Table 1 shows the baseline characteristics of the participants. The number of participants of non-smokers and passive smokers was 447 and 242, respectively. Passive smokers were somewhat younger (p = 0.036) and more likely to belong to junior and senior high schools (p = 0.001) compared with non-smokers. Only a few senior high school teachers (31 in number) were available because of the uniqueness of the municipal high school in Nara City.
Table 1

Baseline characteristics of the participants

 

Total

Non-smokers*

Passive smokers**

P-value

 

n

(%)

n

(%)

n

(%)

 

Age

       

   <50 years old

367

(53%)

225

(50%)

142

(59%)

0.036

   ≥50 years old

322

(47%)

222

(50%)

100

(41%)

 

Sex

       

   Male

257

(37%)

159

(36%)

98

(40%)

0.137

   Female

432

(63%)

288

(64%)

144

(60%)

 

Managerial position

       

   General teacher

572

(83%)

373

(83%)

199

(82%)

0.269

   Principal or vice-principal

60

(9%)

42

(9%)

18

(7%)

 

   School nurse or dietitian

57

(8%)

32

(7%)

25

(10%)

 

School type

       

   Elementary school

437

(63%)

300

(67%)

137

(57%)

0.001

   Junior high school

221

(32%)

135

(30%)

86

(36%)

 

   High school

31

(4%)

12

(3%)

19

(8%)

 

Attitude towards smoke-free schools

       

   Positive

555

(81%)

357

(80%)

198

(82%)

0.537

   Not positive

134

(19%)

90

(20%)

44

(18%)

 

Total

689

447

242

 

*Non-smokers: Participants who were not exposed to environmental tobacco smoke at baseline

**Passive smokers: Participants who were exposed to environmental tobacco smoke at baseline

Change in HRQOL before and after the enforcement of the smoke-free school policy

Table 2 shows the SF-8 scores at baseline and at follow-up for each group. The category scores of passive smokers at baseline were lower than those of non-smokers for GH (1.4, p = 0.013), SF (2.3, p = 0.001), MH (1.4, p = 0.011), and RE (1.6, p = 0.004). Significant increases were observed after the enforcement of the smoke-free school policy in the scores for MH (0.9; 95% CI, 0.2-1.5) and RE (0.7; 95% CI, 0.0-1.3) in non-smokers, and GH (2.2; 95% CI, 1.2-3.1), VT (1.8; 95% CI, 0.9-2.7), SF (2.7; 95% CI, 1.6-3.8), MH (2.0; 95% CI, 1.0-2.9), and RE (2.0; 95% CI, 1.2-2.8) in passive smokers.
Table 2

SF-8 scores before and after the enforcement of the smoke-free school policy

Group

Domain of SF-8*

Score

 
  

Baseline

Follow-up

P-value

  

Mean ± SD

Mean ± SD

 

Non-smokers

GH

48.3 ± 6.7

48.6 ± 6.7

0.304

 

RP

46.8 ± 6.5

47.2 ± 6.9

0.214

 

VT

47.7 ± 6.3

48.1 ± 5.9

0.256

 

SF

45.8 ± 8.2

46.1 ± 7.8

0.501

 

MH

46.9 ± 6.6

47.7 ± 6.5

0.013

 

RE

47.1 ± 6.9

47.8 ± 6.1

0.040

Passive smokers

GH

46.9 ± 7.2

49.0 ± 7.0

<0.001

 

RP

46.7 ± 6.5

47.3 ± 7.3

0.201

 

VT

47.2 ± 6.8

49.0 ± 6.9

<0.001

 

SF

43.6 ± 8.4

46.2 ± 8.4

<0.001

 

MH

45.5 ± 7.2

47.4 ± 7.2

<0.001

 

RE

45.5 ± 7.3

47.5 ± 6.9

<0.001

*GH: General health, RP: Role-physical, VT: Vitality SF: Social functioning, MH: Mental health, RE: Role-emotional

Table 3 shows the differences of the net changes in the category scores between non-smokers and passive smokers, and the regression coefficients generated by the linear regression analyses. The results of the univariable and multivariable analyses were quite similar. All of the category scores, but for RP among passive smokers, increased significantly more than those among non-smokers.
Table 3

Differences of the net changes in SF-8 scores between non-smokers and passive smokers

Domain of SF-8*

Net changes in SF-8 scores before and after enforcement of the smoke-free school policy

Differences of the net changes in the SF-8 scores between non-smokers and passive smokers

   

Univariable analysis

Multivariable analysis**

 

Non-smokers

Passive smokers

Regression coefficient

(95% CI)

Regression coefficient

(95% CI)

GH

0.3

2.2

1.8

(0.7 - 3.0)

1.8

(0.7 - 2.9)

RP

0.4

0.6

0.2

(-0.9 - 1.3)

0.2

(-1.0 - 1.3)

VT

0.3

1.8

1.5

(0.4 - 2.5)

1.4

(0.3 - 2.5)

SF

0.3

2.7

2.4

(1.0 - 3.8)

2.5

(1.1 - 3.9)

MH

0.9

2.0

1.1

(0.0 - 2.2)

1.2

(0.1 - 2.4)

RE

0.7

2.0

1.3

(0.2 - 2.4)

1.6

(0.5 - 2.7)

*GH: General health, RP: Role-physical, VT: Vitality SF: Social functioning, MH: Mental health, RE: Role-emotional

** Adjusted for sex, age, school type, managerial position, and attitude towards smoke-free school policy

Discussion

The smoke-free school policy was originally introduced to protect pupils from exposure to ETS [17]. It was also expected to encourage smoking teachers to quit or reduce their smoking [18] and to prevent pupils from starting smoking [1921]. Our results implied that a smoke-free school policy would also contribute to improving the HRQOL of non-smoking teachers who are exposed to ETS at school. Although our follow-up study design allowed us to assess the causal relationship between the smoke-free school policy and the changes in HRQOL, this simple before-and-after comparison could not indicate when HRQOL had changed. Further time-series studies are needed to clarify this.

The baseline SF-8 scores of teachers who were regularly exposed to ETS in workplaces were lower than those of non-smokers and also lower than the Japanese National Norms [16], even though the study participants were limited to subjectively healthy persons. This finding is consistent with the previous study [2]. Referring to the studies using SF-8 reporting that patients with Japanese cedar pollinosis had a lower mental component score by 1.7 on the SF-8 than the Japanese National Norm [22], and that university students having any allergic disorders showed lower domain scores by 2.3 on the SF-8 than those having no allergy [23], the differences in the SF-8 scores between non-smokers and passive smokers at baseline were considered to be clinically relevant.

Our follow-up survey results suggest that the elimination of ETS by the enforcement of the smoke-free school policy would improve all categories of SF-8 except for RP among passive smokers, reaching identical levels to those of the non-smokers at follow-up. To our knowledge, the present study is the first follow-up survey to evaluate the effects of a social healthcare intervention using SF-8. Therefore, it is difficult to compare its efficacy with those of other social interventions.

We assessed the HRQOL of the participants using SF-8, the scores of which can be directly compared with the scores obtained from the Medical Outcomes Survey 36-item short form health survey (SF-36) [24, 25], a widely-accepted scale for measuring comprehensive quality of life. A decline in the scores for SF-36 would increase the risk of death and of hospitalization [26], and the scores also predict total healthcare costs [27]. Since SF-8 is a shortened version of SF-36, its accuracy might be inferior to that of SF-36. However, the correlation coefficient of each 8-category scale score between SF-8 and SF-36 was substantially high (Spearman r = 0.56 - 0.87) [16], and it was deemed to be a suitable surrogate for evaluating HRQOL. The primary advantage of SF-8 is its simplicity, and as such, it is better suited for mass screening.

This study had some limitations in its design. First, self-reported secondhand smoke was not verified for the measure of ETS exposure in schools. Since the questionnaire survey for ETS exposure and active smoking were reported to be vulnerable to misclassification [28, 29], biochemical measures, such as expiratory gas carbon monoxide and urine or blood cotinine, would be desirable. However, these methods are time-consuming and costly and cannot identify the source of secondhand smoke. The large number of the participants and the long time between the policy enforcement and the surveys should have minimized the temporary fluctuations in the answers. Second, we did not consider exposure to ETS at home or in other private places. Bridevaux et al. [2] reported that exposure to ETS at home strongly affects HRQOL. Additionally, several studies pointed out the significant relationship between one's physical activity level and HRQOL [3034]. These factors might have confounded the results. Third, findings among teachers cannot be well generalized. The proportion of smokers at baseline (male, 29%; female, 1%) was substantially lower than that of the general population in Japan (male, 40%; female, 10%) [35]. This is probably because schoolteachers are highly educated and are expected to behave as role models for pupils. Fourth, since the baseline survey was carried out in mid-winter and the follow-up survey in early autumn, the shift in seasons might have affected HRQOL. Actually, even among teachers who were not exposed to ETS, some domain scores of the SF-8 significantly improved, though they should not be influenced by the enforcement of the smoke-free school policy. The changes in the scores might partly be seasonal effects. However, we primarily focused on the comparison between non-smokers and passive smokers, and their inter-group comparability was preserved. Fifth, we excluded two domains of the SF-8, PF and BP, from the questionnaire form. According to the SF-8 manual for Japanese, people suffering any physical disorder showed significantly lower category scores particularly in the physical-related domain, such as BP, RP, and PF, than did healthy people [16]. Since the study participants were subjectively healthy teachers, physical-related domains would have little relation to the short-term effects of smoke-free school policy. Therefore, we excluded PF and BP from the questionnaire and included only RP to check its independency. As expected, no significant changes in RP score were seen in either non-smokers or passive smokers. However, our arbitrary alternation of the standardized instrument is a methodological violation, and it would preclude a thorough interpretation of the results. As the previous study suggested a relationship between those physical-related domains and exposure to ETS among nonsmoking women [2], these domains should have been examined as well.

Conclusions

Exposure to ETS in schools lowers HRQOL among non-smoking teachers, and the enforcement of a smoke-free school policy would improve their HRQOL. Our findings should encourage policy makers to push ahead with restricting smoking in schools.

List of abbreviations

ETS: 

environmental tobacco smoke

HRQOL: 

health-related quality of life

COPD: 

chronic obstructive pulmonary disease

SF-8: 

Medical Outcomes Survey Short Form-8 questionnaire

GH: 

general health perception

PF: 

physical functioning

RP: 

role functioning physical

BP: 

bodily pain

VT: 

vitality

SF: 

social functioning

MH: 

mental health

RE: 

role functioning emotional

CI: 

confidence interval

SF-36: 

Medical Outcomes Survey 36-item short form health survey.

Declarations

Acknowledgements

This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Health, Labor, and Welfare of Japan. We gratefully acknowledge the Board of Education of Nara City for its approbation of our survey. We also would like to thank Dr. Paul Matychuk for language support.

Authors’ Affiliations

(1)
Kyoto University Health Service, Yoshida-Honmachi
(2)
Public Health Center
(3)
Health Administration Center, Nara Women's University, Kitauoya-Nishimachi

References

  1. U.S. Department of Health and Human Services: The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. 2006.Google Scholar
  2. Bridevaux PO, Cornuz J, Gaspoz JM, Burnand B, Ackermann-Liebrich U, Schindler C, Leuenberger P, Rochat T, Gerbase MW: Secondhand smoke and health-related quality of life in never smokers: results from the SAPALDIA cohort study 2. Arch Intern Med 2007,167(22):2516–2523. 10.1001/archinte.167.22.2516PubMedView ArticleGoogle Scholar
  3. Sippel JM, Pedula KL, Vollmer WM, Buist AS, Osborne ML: Associations of smoking with hospital-based care and quality of life in patients with obstructive airway disease. Chest 1999,115(3):691–696. 10.1378/chest.115.3.691PubMedView ArticleGoogle Scholar
  4. Eisner MD, Balmes J, Yelin EH, Katz PP, Hammond SK, Benowitz N, Blanc PD: Directly measured secondhand smoke exposure and COPD health outcomes. BMC Pulm Med 2006, 6: 12. 10.1186/1471-2466-6-12PubMed CentralPubMedView ArticleGoogle Scholar
  5. Allwright S, Paul G, Greiner B, Mullally BJ, Pursell L, Kelly A, Bonner B, D'Eath M, McConnell B, McLaughlin JP, et al.: Legislation for smoke-free workplaces and health of bar workers in Ireland: before and after study. BMJ (Clinical research ed) 2005,331(7525):1117. 10.1136/bmj.38636.499225.55View ArticleGoogle Scholar
  6. Farrelly MC, Nonnemaker JM, Chou R, Hyland A, Peterson KK, Bauer UE: Changes in hospitality workers' exposure to secondhand smoke following the implementation of New York's smoke-free law. Tob Control 2005,14(4):236–241. 10.1136/tc.2004.008839PubMed CentralPubMedView ArticleGoogle Scholar
  7. Fichtenberg CM, Glantz SA: Association of the California Tobacco Control Program with declines in cigarette consumption and mortality from heart disease. N Engl J Med 2000,343(24):1772–1777. 10.1056/NEJM200012143432406PubMedView ArticleGoogle Scholar
  8. Pechacek TF, Babb S: How acute and reversible are the cardiovascular risks of secondhand smoke? BMJ 2004,328(7446):980–983. 10.1136/bmj.328.7446.980PubMed CentralPubMedView ArticleGoogle Scholar
  9. Menzies D, Nair A, Williamson PA, Schembri S, Al-Khairalla MZ, Barnes M, Fardon TC, McFarlane L, Magee GJ, Lipworth BJ: Respiratory symptoms, pulmonary function, and markers of inflammation among bar workers before and after a legislative ban on smoking in public places. Jama 2006,296(14):1742–1748. 10.1001/jama.296.14.1742PubMedView ArticleGoogle Scholar
  10. Tredaniel J, Boffetta P, Saracci R, Hirsch A: Exposure to environmental tobacco smoke and risk of lung cancer: the epidemiological evidence. Eur Respir J 1994,7(10):1877–1888. 10.1183/09031936.94.07101877PubMedView ArticleGoogle Scholar
  11. Council NR: Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects. National Academy Press; 1986.Google Scholar
  12. Dahms TE, Bolin JF, Slavin RG: Passive smoking. Effects on bronchial asthma. Chest 1981,80(5):530–534. 10.1378/chest.80.5.530PubMedView ArticleGoogle Scholar
  13. Bascom R, Kulle T, Kageysobotka A, Proud D: Upper Respiratory-Tract Environmental Tobacco-Smoke Sensitivity. American Review of Respiratory Disease 1991,143(6):1304–1311.PubMedView ArticleGoogle Scholar
  14. Bascom R, Kesavanathan J, Permutt T, Fitzgerald TK, Sauder L, Swift DL: Tobacco smoke upper respiratory response relationships in healthy nonsmokers. Fundam Appl Toxicol 1996,29(1):86–93. 10.1006/faat.1996.0009PubMedView ArticleGoogle Scholar
  15. Danuser B, Weber A, Hartmann AL, Krueger H: Effects of a Bronchoprovocation Challenge Test with Cigarette Sidestream Smoke on Sensitive and Healthy-Adults. Chest 1993,103(2):353–358. 10.1378/chest.103.2.353PubMedView ArticleGoogle Scholar
  16. Fukuhara S, Suzukamo Y: Manual of the SF-8 Japanese edition. Kyoto: Institute for Health Outcomes & Process Evaluation Research; 2004.Google Scholar
  17. Wold B, Torsheim T, Currie C, Roberts C: National and school policies on restrictions of teacher smoking: a multilevel analysis of student exposure to teacher smoking in seven European countries. Health education research 2004,19(3):217–226. 10.1093/her/cyg029PubMedView ArticleGoogle Scholar
  18. Fichtenberg CM, Glantz SA: Effect of smoke-free workplaces on smoking behaviour: systematic review. BMJ (Clinical research ed) 2002,325(7357):188. 10.1136/bmj.325.7357.188View ArticleGoogle Scholar
  19. Barnett TA, Gauvin L, Lambert M, O'Loughlin J, Paradis G, McGrath JJ: The influence of school smoking policies on student tobacco use. Arch Pediatr Adolesc Med 2007,161(9):842–848. 10.1001/archpedi.161.9.842PubMedView ArticleGoogle Scholar
  20. Moore L, Roberts C, Tudor-Smith C: School smoking policies and smoking prevalence among adolescents: multilevel analysis of cross-sectional data from Wales. Tobacco control 2001,10(2):117–123. 10.1136/tc.10.2.117PubMed CentralPubMedView ArticleGoogle Scholar
  21. Poulsen LH, Osler M, Roberts C, Due P, Damsgaard MT, Holstein BE: Exposure to teachers smoking and adolescent smoking behaviour: analysis of cross sectional data from Denmark. Tobacco control 2002,11(3):246–251. 10.1136/tc.11.3.246PubMed CentralPubMedView ArticleGoogle Scholar
  22. Fujii T, Ogino S, Arimoto H, Irifune M, Iwata N, Ookawachi I, Kikumori H, Seo R, Takeda M, Tamaki A, et al.: Quality of life in patients with Japanese cedar pollinosis: using the SF-8 health status questionnaire (Japanese version). Arerugi 2006,55(10):1288–1294.PubMedGoogle Scholar
  23. Takeuchi N, Ito M, Ogino S: Assessment of quality of life in university students with the SF-8 health status questionnaire Japanese version -Influence by allergic disease and the eating custom of yogurt: for freshmen of Osaka University-. JJIAO 2008,26(4):297–302.Google Scholar
  24. Fukuhara S, Bito S, Green J, Hsiao A, Kurokawa K: Translation, adaptation, and validation of the SF-36 Health Survey for use in Japan. J Clin Epidemiol 1998,51(11):1037–1044. 10.1016/S0895-4356(98)00095-XPubMedView ArticleGoogle Scholar
  25. Ware JE Jr, Sherbourne CD: The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992,30(6):473–483. 10.1097/00005650-199206000-00002PubMedView ArticleGoogle Scholar
  26. Fan VS, Au D, Heagerty P, Deyo RA, McDonell MB, Fihn SD: Validation of case-mix measures derived from self-reports of diagnoses and health. J Clin Epidemiol 2002,55(4):371–380. 10.1016/S0895-4356(01)00493-0PubMedView ArticleGoogle Scholar
  27. Hornbrook MC, Goodman MJ: Chronic disease, functional health status, and demographics: a multi-dimensional approach to risk adjustment. Health Serv Res 1996,31(3):283–307.PubMed CentralPubMedGoogle Scholar
  28. Jaakkola MS, Jaakkola JJ: Assessment of exposure to environmental tobacco smoke. Eur Respir J 1997,10(10):2384–2397. 10.1183/09031936.97.10102384PubMedView ArticleGoogle Scholar
  29. Willemsen MC, Brug J, Uges DR, Vos de Wael ML: Validity and reliability of self-reported exposure to environmental tobacco smoke in work offices. Journal of occupational and environmental medicine/American College of Occupational and Environmental Medicine 1997,39(11):1111–1114.PubMedView ArticleGoogle Scholar
  30. Shibata A, Oka K, Nakamura Y, Muraoka I: Recommended level of physical activity and health-related quality of life among Japanese adults. Health and quality of life outcomes 2007, 5: 64. 10.1186/1477-7525-5-64PubMed CentralPubMedView ArticleGoogle Scholar
  31. Vuillemin A, Boini S, Bertrais S, Tessier S, Oppert JM, Hercberg S, Guillemin F, Briancon S: Leisure time physical activity and health-related quality of life. Preventive medicine 2005,41(2):562–569. 10.1016/j.ypmed.2005.01.006PubMedView ArticleGoogle Scholar
  32. Brown DW, Balluz LS, Heath GW, Moriarty DG, Ford ES, Giles WH, Mokdad AH: Associations between recommended levels of physical activity and health-related quality of life. Findings from the 2001 Behavioral Risk Factor Surveillance System (BRFSS) survey. Preventive medicine 2003,37(5):520–528. 10.1016/S0091-7435(03)00179-8PubMedView ArticleGoogle Scholar
  33. Laforge RG, Rossi JS, Prochaska JO, Velicer WF, Levesque DA, McHorney CA: Stage of regular exercise and health-related quality of life. Preventive medicine 1999,28(4):349–360. 10.1006/pmed.1998.0429PubMedView ArticleGoogle Scholar
  34. Morimoto T, Oguma Y, Yamazaki S, Sokejima S, Nakayama T, Fukuhara S: Gender differences in effects of physical activity on quality of life and resource utilization. Qual Life Res 2006,15(3):537–546. 10.1007/s11136-005-3033-2PubMedView ArticleGoogle Scholar
  35. The National Health and Nutrition Survey in Japan 2006. [http://www.mhlw.go.jp/houdou/2008/04/dl/h0430–2c.pdf]

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© Kiyohara et al; licensee BioMed Central Ltd. 2010

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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