OBJECTIVE: To examine the relationship between CO levels and putative factors including smoking status among residents of Karachi, an urban center with very high levels of air pollution.
METHODS: Two hundred and eighteen volunteering subjects were asked to maximally exhale into a Smokerlyzer breath CO analyzer. Each of the volunteers was also asked to reply to a questionnaire-based interview seeking demographic information as well as details of exposure to tobacco, traffic fumes and other air pollutants.
RESULTS: Out of the 218 participating subjects, 75% were males and 27% were current or ex-smokers. The mean CO level was 2.92 parts per million (ppm). Cigarette smoking was the only factor found to influence CO levels. Number of cigarettes smoked per day was directly related to CO levels, while time since the last smoke was inversely related. There was no difference in CO levels between ex-smokers and never-been-smokers. Years of residence in Karachi, quantitative exposure to traffic and perception of occupational exposure to air pollutants were not associated with CO levels.
CONCLUSIONS: Smoking status, number of cigarettes smoked per day and time since last smoke correlated well with exhaled breath CO levels, in spite of high air pollution levels. This tool therefore continues to provide a valid and real-time assessment of a subject\u27s current smoking status

Haque, Suleman

Khan, Javaid

Khan, Sumera

Khawaja, M. Rizwanulhaq

Shafiq, Majid

eCommons@AKU

eCommons@AKUSection of Pulmonary & Critical Care Department of MedicineFebruary 2008Socio-demographic correlates of exhaled breathcarbon monoxide in Karachi's adult populationMajid ShafiqAga Khan UniversitySumera KhanAga Khan UniversityM. Rizwanulhaq KhawajaAga Khan UniversitySuleman HaqueAga Khan UniversityJavaid KhanAga Khan UniversityFollow this and additional works at: http://ecommons.aku.edu/pakistan_fhs_mc_med_pulm_critcarePart of the Respiratory System Commons, Respiratory Tract Diseases Commons, and theSubstance Abuse and Addiction CommonsRecommended CitationShafiq, M., Khan, S., Khawaja, M., Haque, S., Khan, J. (2008). Socio-demographic correlates of exhaled breath carbon monoxide inKarachi's adult population. Journal of the Pakistan Medical Association, 58(2), 75-8.Available at: http://ecommons.aku.edu/pakistan_fhs_mc_med_pulm_critcare/13Introduction Cigarette smoking is responsible for considerablemorbidity and morbidity worldwide.1,2 With increasingmedical evidence as well as public awareness vis-à-vis thesame, smoking cessation programmes are assuming ever-increasing importance. Accurate determination of smoking status isimportant in order to establish the efficacy of interventionsaimed at smoking cessation. For a patient who isundergoing a cessation programme, a tool that takes intoaccount recent smoking habits needs to be employed inorder to promptly detect a relapse. The question of smokingstatus also assumes vital importance in certain instances ofmedical decision-making, e.g. a physician may decideagainst placing a prospective candidate on the lungtransplant eligibility list in case the patient does not exhibitabstinence from smoking.3So what is a reliable and convenient means of assessingcurrent smoking status? There is clear evidence that self-reporting of smoking habits may underestimate the smokingstatus, both qualitatively (i.e. whether smoking or not) andquantitatively (i.e. number of cigarettes smoked daily).4In recent times, biochemical markers of smokingstatus have attracted increased scientific interest. Sincecigarette smoking is known to be associated with increasedblood levels of carboxy haemoglobin (COHb), exhaledbreath carbon monoxide (CO) levels have receivedconsiderable attention. Studies have already shown thatbreath CO levels can accurately predict smoking status in anumber of populations.5In order for CO levels to be a useful qualitative aswell as quantitative indicator of smoking status, CO levelsamong non-smoking controls must also be determined forthe population under question. This is important in order toexclude the effect that other variables (such as air pollutionor gas heaters) may have on CO levels. In Pakistan, a developing country that is the sixthmost populous in the world, the epidemiology of baselinebreath CO levels among non-smoking adults is not known.Moreover, in heavily populated urban centers withunchecked air pollution levels and absence of environment-protective traffic laws and green belts, it remains to beestablished whether or not there is a distinct difference inCO levels between smokers and non-smokers.In this initial survey, we aimed to estimate baselineexhaled breath CO levels and its predictors in a sample fromthe resident population of Karachi, Pakistan's mostpopulous urban center. Subjects and MethodsThis cross sectional study was conducted on patientsand attendants visiting a Pulmonology clinic at the AgaOriginal ArticleSocio-demographic correlates of exhaled breath carbon monoxide in Karachi'sadult populationMajid Shafiq, Sumera Khan, M Rizwanulhaq Khawaja, Suleman Haque, Javaid A KhanSection of Pulmonary and Critical Care, Department of Medicine. Aga Khan University, Karachi.AbstractObjective: To examine the relationship between CO levels and putative factors including smoking status amongresidents of Karachi, an urban center with very high levels of air pollution. Methods: Two hundred and eighteen volunteering subjects were asked to maximally exhale into aSmokerlyzer™ breath CO analyzer. Each of the volunteers was also asked to reply to a questionnaire-basedinterview seeking demographic information as well as details of exposure to tobacco, traffic fumes and other airpollutants.Results: Out of the 218 participating subjects, 75% were males and 27% were current or ex-smokers. The meanCO level was 2.92 parts per million (ppm). Cigarette smoking was the only factor found to influence CO levels.Number of cigarettes smoked per day was directly related to CO levels, while time since the last smoke wasinversely related. There was no difference in CO levels between ex-smokers and never-been-smokers. Years ofresidence in Karachi, quantitative exposure to traffic and perception of occupational exposure to air pollutantswere not associated with CO levels. Conclusions: Smoking status, number of cigarettes smoked per day and time since last smoke correlated wellwith exhaled breath CO levels, in spite of high air pollution levels. This tool therefore continues to provide a validand real-time assessment of a subject's current smoking status (JPMA 58:75;2008).Vol. 58, No. 2, February 2008 75Khan University Hospital (AKUH), Karachi. The inclusioncriteria were as follows: all subjects were at least 18 yearsold, and had been residents of Karachi for the greater part ofthe past two years. Subjects with any chronic or recurrentpulmonary disease were excluded from the study. Since thestudy was performed in fall season, which is characterizedby very warm temperatures in Karachi, domestic heatingsystems were assumed to play no role whatsoever in thestudy findings.Two hundred and eighteen subjects were recruitedthrough convenience sampling and a structuredquestionnaire-based interview was carried out by a doctor inthe local language (Urdu). The questionnaire was initiallydrafted on the basis of literature review, after which twoclinical pulmonologists were separately asked to review it.The preliminary questionnaire was pre-tested on 25 patientsand attendants and modified to address the identifieddeficiencies.The questionnaire's first section recordeddemographic characteristics as well as years of residence inKarachi, nature of occupation (if any) and perception ofexposure to air pollutants at workplace. Questionsconcerning smoking status, including passive smoking athome or workplace, ex-smoker status, number of cigarettessmoked daily and time (in hours) since the last smoke wereincluded in the second section of the questionnaire.According to National Health Interview Survey, 1992definition, any smoker who claimed to be not smoking "atall" currently was considered as an ex-smoker.6 Subjectswere also asked about alternative forms of tobaccoconsumption, including hookah and sheesha (variants ofpiped smoke) and were also asked to quantify their durationof exposure to vehicular traffic on a usual day.Next, exhaled breath CO levels were measured inparts per million (ppm) using a CO breath analyzer(Smokerlyzer™). Patients were asked to hold their breathfor as close to 10 seconds as possible, then expire fully intothe breath analyzer via a disposable mouth-piece. A doctormade a demonstration before supervising the exercise, andthose subjects who failed to conduct the test properly had torepeat it.The study was conducted in compliance with"Ethical principles for medical research involving humansubjects" as per the Helsinki Declaration. Participants'identity was not sought or recorded. Verbal informedconsent was obtained from all participants. Data was entered and analyzed in Statistical Packagefor Social Sciences 13.0 (SPSS 13.0). One-way analysis ofvariance (ANOVA), Student's t-test and linear regressionwere employed to test for putative associations between COlevels and each of various factors. For all purposes, a p-value of <0.05 was considered as the criterion ofsignificance.ResultsThere were 218 participants in total, of which 161were males and 55 females. Mean period of residence inKarachi was 31 years. Table 1 illustrates the other socio-demographic characteristics. Median duration spent in the traffic per day was 2hours. Thirty-seven percent of subjects drove in air-conditioned vehicles daily, 41% in vehicles with openwindows and 22% did not drive on a daily basis. Twentypercent stated that they were exposed to inhaled pollutantsat their workplace. Sixteen percent were self-reportedsmokers, another 11% being ex-smokers. Twenty-fivepercent and 16% said they were exposed to passive smokingat work place and at home, respectively. The mean exhaled breath carbon monoxide (CO)level in the overall population was 2.92 parts per million(ppm). The mean exhaled breath CO levels in variousdemographic groups of our sample are shown in Table 1.Male smokers had a higher mean CO level (3.26 vs. 1.98ppm; p<0.05). However, males who had never smoked hadresults 1.81 vs. 1.98 ppm. The difference in mean exhaledCO levels in different age groups was not statisticallysignificant (one-way ANOVA F=8.49, df=36, p=0.3). In alinear regression model, age, number of years of residencein Karachi or number of hours per day in traffic were notassociated with CO levels. Traveling in an air-conditionedTable 1. Socio-demographic features of a Karachi population.Variable Number (%) Mean exhaled CO ± SD (ppm)OverallAge (in years)<2526-40>40Gender*MaleFemaleEducation (in years)<56-1011-14>14Smoking status*Current smokersEx-smokersNever-been-smokers21851 (23)69 (32)98 (45)161 (75)55 (25)13 (6)58 (27)109 (50)38 (17)35 (16)23 (11)160 (73)2.92±0.32.14±0.33.16±0.53.15±0.53.26±0.41.98±0.33.08±0.72.38±0.42.93±0.43.66±0.98.54±1.21.83±0.21.86±0.1[*Statistically significant association with CO levels]76 J Pak Med Assocversus openly ventilated vehicle did not have any impact onCO levels. Perception of being occupationally exposed toinhaled pollutants was not associated with higher CO levels(3.93 vs. 2.66 ppm; (p<0.07). Current smokers had a higher mean CO level thannever-been-smokers (8.54 vs. 1.86 ppm) (p=0.01) or ex-smokers (8.54 ppm vs. 1.83 ppm) (p=0.01). Moreover, asdepicted in Table 2, CO levels increased with increasingnumbers of cigarettes smoked per day (p=0.01). In a linearregression model, time since the last smoke (in hours) wasinversely related to CO level (p=0.01). Every additionalhour lapsed reduced the CO level by 0.42 ppm (regressioncoefficient) and this factor alone explained 33.8% of thevariability (R2) in the CO levels among smokers.Out of the 35 current smokers, 32 had levels higherthan 7 ppm (91% sensitivity), while 153 out of 179 currentnon-smokers had levels below 7 ppm (85% specificity).This was found to be the optimal cut-off for predictingsmoking status. Reduction of the cut-off to 3 ppm wasneeded in order to take the negative predictive value to100%.Ten subjects said they consumed alternative forms oftobacco. Of these, only one respondent claimed a minimumconsumption frequency of once every week. Among non-smokers, there was no statisticallysignificant difference in the mean CO levels of ex-smokersand never-been-smokers (1.83 vs. 1.86 ppm, respectively).Similarly, exposure to passive smoking at work place orhome did not have any association with CO levels. DiscussionWe chose as our study population the residents ofKarachi, which is the largest urban center as well as theeconomic capital of Pakistan. Vehicular traffic on the mainroads of Karachi is one of the busiest in the country, andinfrequent monitoring by the law-enforcement agenciescontributes to a substantial proportion of vehicles emittinglarge amounts of pollutants in defiance of existing trafficlaws. There is heavy traffic congestion on most roads duringa large port of the day, which increases duration of exposureto traffic pollutants. To make matters worse, there are fewroads with any plantation on either side, and few parts of thecity have any provision for green belts. A recent studycarried out by the Pakistan Space and Upper AtmosphereResearch Commission (SUPARCO) confirmed the highlevels of air pollution in Karachi, although a few urbancenters had even higher levels.7The prevalence of self-reported smoking asestimated from our sample was 16%, which is similar to thefigure of 15.2% reported in Ahmad K et al's analysis of datafrom the National Health Survey of Pakistan (NHSP) 1990-1994.8 The mean CO level among never-been-smokers was1.86, compared to 8.54 among current smokers. The optimalcut-off value for predicting smoking status was found to be7 ppm. This is somewhat lower than the values reported bymost Western studies, but closer to the cut-off of 6.5 ppmrecently reported from Turkey.5 On the other hand, adramatic reduction in the cut-off value was required in orderto take the negative predictive value to maximum, anobservation supported by various studies.9 Thus, if it isimportant to screen out every case of a violation of smokingcessation, a cut-off around 3 ppm would be moreappropriate. However, given the small size of this sample, itis advised to be when generalizing these results. It issuggested that more extensive studies be carried out toestablish the optimal cut-offs for this population and setting.In a developing country with limited resources likePakistan, the preferred diagnostic tool or therapeuticintervention is all the more dictated by factors other thandiagnostic validity and clinical efficacy. Cost, degree ofexpertise involved and indeed local availability are usuallythe over-riding issues. In this context, measurement of theexhaled breath CO level stands quite favourably as a usefultool. The equipment is easy to use and read off, the test isquick to administer, and the patient need not be additionallycharged for using a couple of disposable mouth-pieces. An additional advantage over the conventional self-reported assessment tools in this setting would be the factthat in Pakistan's multi-lingual society (with over fivelanguages commonly spoken, Urdu not understood by asignificant minority and translators regularly needed inhospitals), measuring the CO level circumvents the need (toan extent) for interviewing the patient on current smokinghabits.While perception of occupational exposure topollutants was not found to be associated with CO levels,authors note with interest the relevant p-value of 0.07. It isplausible that there may well be an association which wasnot covered due to the limited sample size of this study. Inany case, we do suggest that this finding mandates moreextensive research into this relationship in our setting. The sample was derived from visitors attending aTable 2. Number of cigarettes per day and mean exhaled CO level(ppm) among smokers of a Karachi population.No. ofCigarettes / dayNo. of SmokersMean exhaledCO (ppm)One wayANOVA<11-56-1011-20>202129591.003.427.338.4016.67F-value 8.49df = 36p<0.001Vol. 58, No. 2, February 2008 77Pulmonology clinic at the Aga Khan University Hospital(AKUH). AKUH is a privately owned, 500-bed tertiarylevel hospital, offering some of the most state-of-the-artdiagnostic and therapeutic facilities in the country. It isconceivable that a relatively higher proportion of peoplevisiting these clinics would belong to affluent and educatedfamilies. This is significant in the sense that according to theNHSP 1990-1994, illiteracy was associated with a higherprevalence of cigarette smoking.8 This is, however, unlikelyto make a bearing on our findings vis-à-vis the relationshipof CO levels to various putative factors including smokingstatus.Moreover, our comparison of various groups amongsmokers on the basis of number of cigarettes smoked perday (Table-2) might lack an ideal validity due to a relativelylimited number of smokers in the overall study sample. Itfollows that more extensive studies are needed to furtherexamine this relationship.We conclude that in spite of high air pollution levels,the exhaled breath CO level continues to provide a valid andreal-time assessment of a subject's current smoking status.Larger studies are required in order to definitively establishthe optimal cut-off values for predicting smoking status aswell as for detecting violation of smoking cessation.We also recommend additional studies to explore therelationship between occupational exposure and CO levelsin this setting.AcknowledgementsThe authors gratefully acknowledge the contributionof Department of Medicine, Aga Khan University Hospital,for examining and approving the protocol of this study. References1. Zhang H, Cai B. The impact of tobacco on lung health in China. Respirology2003;8:17-212. Shopland DR. Tobacco use and its contribution to early cancer mortality witha special emphasis on cigarette smoking. Environ Health Perspect1995;103(suppl8):131-42.3. International guidelines for the selection of lung transplant candidates. TheAmerican Society for Transplant Physicians (ASTP)/American ThoracicSociety(ATS)/European Respiratory Society(ERS)/International Society forHeart and Lung Transplantation(ISHLT). Am J Respir Crit Care Med1998;158:335-9.4. Pearce MS, Hayes L. Self-reported smoking status and exhaled carbonmonoxide: results from two population-based epidemiologic studies in theNorth of England. Newcastle Heart Project; Newcastle Thousand FamiliesStudy. Chest 2005;128:1233-8.5. Deveci SE, Deveci F, Acik Y, Ozan AT. The measurement of exhaled carbonmonoxide in healthy smokers and non-smokers. Respir Med 2004;98:551-66. Cigarette smoking among adults-United States, 1992, and changes in thedefinition of current cigarette smoking [published erratum appears in MMWRMorb Mortal Wkly Rep 1994;43:801-3]. MMWR Morb Mortal Wkly Repl994;43:342-6.7. Ghauri B, Lodhi A, Mansha M. Development of baseline (air quality) data inPakistan. Environ Monit Assess 2006; [Epub ahead of print]8. Ahmad K, Jafary F, Jehan I, Hatcher J, Khan AQ, Chaturvedi N, Jafar TH.Prevalence and predictors of smoking in Pakistan: results of the NationalHealth Survey of Pakistan. Eur J Cardiovasc Prev Rehabil 2005;12:203-89. Javors MA, Hatch JP, Lamb RJ. Cut-off levels for breath carbon monoxide asa marker for cigarette smoking. Addiction 2005;100:159-6.Review ArticleRole of exercise in osteoporosis prevention - Current concepts Mozaffer Rahim Hingorjo1, Sadiqa Syed2, Masood A.Qureshi3Department. of Physiology1,2, Fatima Jinnah Dental College, Karachi, Department of Physiology3, Dow International Medical College, Dow University ofHealth Sciences, Karachi.AbstractOsteoporosis is a metabolic disorder of the bones dueto loss of both bone mineral and bone matrix in equalproportions resulting in a bone that is weak and unable tosupport the body. This becomes a problem in the elderly whoare then at risk of frequent fractures increasing the morbidityand mortality. Measures taken early in life in the form ofcalcium and exercise go far in preventing the development ofthis disorder. The primary purpose of this narrative review isto evaluate the current literature and to provide insight intothe role of exercise relating to osteoporosis. Emphasis isgiven to the importance of the specific types of exercisesneeded to increase bone strength and muscle power, keepingin view the age and general physical condition of the person.IntroductionOSTEOPOROSIS is defined by the NIH ConsensusDevelopment Panel on Osteoporosis as "a skeletal disordercharacterized by compromised bone strength predisposing aperson to an increased risk of fracture."1 The WHO WorkingGroup has defined osteoporosis according to themeasurement of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA). A T-score value of2.5 standard deviation or more below the young adult meanis considered diagnostic for osteoporosis.2Bone mineral density at any time in life dependsupon the peak bone density achieved during thedevelopment and growth period (especially at the time ofpuberty) and the subsequent adult bone loss. Regular78 J Pak Med Assoc

Socio-demographic correlates of exhaled breath carbon monoxide in Karachi\u27s adult population

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Socio-demographic correlates of exhaled breath carbon monoxide in Karachi\u27s adult population

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