Lipid Profile in Opium Users: Results of Fasa PERSIAN Cohort Study, First Phase


 Background: One of the main health problems in many societies is the increase of opium abuse which correlated with many problems such as cardiovascular disease. The goal of our study is to evaluate the correlation of opium use with blood lipoproteins as risk factors of CVD.Methods: This is a cross-sectional study on participants of the first phase of the PERSIAN Cohort study who were 35 -70 years old. Demographic characteristics, history of smoking, alcohol, and opium consumption, medical history and medications were asked and checklists were filled out. level of physical activity and fat intake was registered. lipoprotein profiles were investigated by blood sampling. IBM SPSS Statistics v21 was used to analyze the correlation of opium and lipid profile and the significant level was <0.05.Results: From 9300 participants with a mean age of 48.06±9.44 years old, 49.6% were male. About 24.1% of participants used opium. The level of total cholesterol (adjusted p= 0.02) and HDL (adjusted p= 0.04) in people who used opium was significantly lower than others. But, the level of triglyceride (p=0.11) and LDL (adjusted p= 0.06) was not different in users and non-users. LDL (OR=0.8, adjusted p= 0.009) and total cholesterol (OR=0.81, adjusted p= 0.007) had normal level in people who used opium than non-consuming people.Conclusion: This study showed that there is correlation between opium usage and lower level of total cholesterol and LDL, however the lower level of HDL in normal range was seen in opium users.


Introduction
Due to the World Drug Report, about 58 million people of the world's adult population used one type of opium in 2018 (1). Evidence showed that opium is traditionally used in many south and central Asian countries, including India, Iran, Afghanistan, and Pakistan (2).In these cultures people believe that opium usage is effective in the control of blood sugar, blood pressure, and lipids that is one of the causes of increasing the prevalence of opium usage in middle age and elderly (3). In total, the prevalence of drug abuse increasing unfortunately and addiction is being one of the important issues of the day. The prevalence of opium usage in Iran varies from 8.9%in rural areas of Babol (4) to 17% in Golestan (5) and 24.7% in the rural areas of kerman (6). Cardiovascular, respiratory, and Central Nervous Systems are mostly affected by the usage of opium. Most studies showed that the opium usage increase risk of acute myocardial infarction, atherosclerosis and cardiovascular mortality (7). Also, opium usage increases the risk of many cancers such as lung, esophageal, gastric, laryngeal and bladder cancer (2).
Lipid pro les are known as risk factors of cardiovascular disease and many studies assessed the correlation of opium and lipid levels. Aghadavoudi et al. showed that LDL and triglyceride levels in drug addicts were higher than non-drug-dependent groups (8). In a study by Fatemi SS et al. is con rmed that cholesterol, triglyceride and LDL-c signi cantly reduced in people who consumed opium compared with people who did not consume this (9). While in other studies it has been pointed out that the levels of triglyceride, total cholesterol, and LDL were signi cantly increased in the drug addict group, but HDL levels did not change signi cantly (10). There are many controversies about the effect of opium on lipid pro le. To investigate the correlation of opium and lipid pro le There are many confounding factors that affect, such as smoking and alcohol consumption. So, in this study correlation of opium and lipid pro le was evaluated considering these confounding factors in a remarkable population with a su cient sample size of who used opium in the Fasa cohort study.

Methods And Materials Study design and participants
This study is a cross-sectional study as the rst phase of a longitudinal Fasa branch of PERSIAN (prospective Epidemiological Research Study in Iran) cohort study on the population of Fasa, south of Iran. Geographically Fasa is a city in a southeast of Fars province with total population of about 250,000 people. One of the districts is called Sheshdeh (28°56′56.0″N53°59′26.9″E) which contain of 41,000 people was chosen for Fasa cohort study. people in the age range of 35-70 years old were invited to this study who were about 10000 people. The protocol of this population-based mega project has in presented by Malekzadeh and Farjam et al. in 2016 (11-13).
people who were using medication which affect lipid pro le such as additive containing Alcohol- History of smoking, opium and alcohol usage was taken. Participants were asked if they are active current smoker, use opium derived products or alcohol frequently in a week. There are many confounding factors such as age, gender, BMI, Fat intake, medications, smoking and alcohol consumption that were used as confounder in regression model.

Statistical Analysis
The univariable statistical analysis was performed by using Chi square, t-test, ANOVA and Pearson correlation tests. Multivariable linear and logistic regression model analysis was done using enter selection of p < 0.2. IBM SPSS Statistics v21 was used and P-value < 0.005 was considered as signi cance level.
Due to the importance of high lipid pro le as risk factor for many diseases such as cardio vascular, we analyzed correlation of opium usage and abnormal level of lipid pro le in present of other variable and confounders in logistics regression model, (Table 3).

Discussion
This study was conducted on the rural population of Fasa PERSIAN cohort study with a mean age of 48 years old. The prevalence of opium usage was 24 people per 100 individuals. The frequency of current cigarette smoking and regular alcohol drinking was 27% and 2%, respectively. One of the considerable causes for the high prevalence of opium abuse in this study compare to others (4,5,14) is the location of Fasa city in the route of transportation of opium. Mainly The route of transportation of drugs into the country from the eastern border (Kerman province) and from the southern borders (Hormuzgan province) crosses the city of Fasa. So, people have more access to this kind of substance (15).
Due to Middle Eastern societies people belief that traditionally consumption of opium is effective for control blood pressure, lipids and glucose and to prevent heart diseases (16), there are many studies with different results about opium effects on lipid pro le. Some studies have suggested that opium use has no signi cant effect on total cholesterol, LDL, or HDL-C (17). In contrast, a study by Fatemi SS et al. is con rmed that LDL signi cantly reduced in people who consumed opium (9). While other studies pointed out that the levels of triglyceride, total cholesterol, and LDL were signi cantly increased in the drug addict group, but HDL levels did not change signi cantly in rabbits (10). In a systematic review and metaanalysis study on diabetic patients, results showed that total cholesterol was lower in opium abusers but no signi cant changes were shown in other lipid pro le between users and non-users (18). Furthermore, our nding demonstrated that opium users had lower levels of total cholesterol, LDL and HDL in comparison with non-users. But opium usage had no correlation with the TG level.
The relationship between low cholesterol level and opioid signaling has been studied previously (4). Lipid rafts microdomains exist in the outer layer of the plasma membrane and contain high levels of cholesterol. Also, these microdomains host opioid receptors including µ-opioid receptor (MOR), κ opioid receptors (KOR), and δ-opioid receptors (DOR) as well as a variety of signaling factors such as G proteincoupled receptors (GPCR) (19,20). The process of opioid signaling has many steps including desensitization, phosphorylation, internalization, and resensitization. Internalization considers as the primary step that leads to the resensitization of the opioid receptors (4). It has been reported that Cholesterol depletion reduces the internalization of δ-opioid receptors in HEK293 cells (6). According to Zheng et al., reducing the cholesterol level by simvastatin, disrupts the opioid signaling in the cultured neurons and decreases the analgesic effect of opioids in a mouse model (1). Also, a clinical study conducted by Huang et al. indicated that patients with low levels of cholesterol may require higher doses of opioids to reduce their pain (5). Taken together it seems that cholesterol has an important role in the opioid signaling.
Our result showed signi cantly lower levels of cholesterol among opium users. Also, we mentioned the previous studies emphasizing that low cholesterol levels impair the opioid signaling. However, the chronology of low cholesterol levels and opioid tolerance among amusers is not clear yet. Experimental and clinical studies should be conducted to determine if opium abuse causes low cholesterol levels or low cholesterol level accelerates the process of tolerance in opioid abusers? It is known that opioid abuse dramatically changes the diet and causes loss of appetite and malnutrition in most cases (3). It is possible that lack of proper diet leads to reduced cholesterol levels in the opium abusers that cause more opioid tolerance and consequently these individuals require increasing opium dose over time. However, this hypothesis requires precise studies to prove.
While, lower levels of cholesterol in opium abusers could be due to decrease of appetite and nutritional de ciency in them (21,22), it was shown that opiate agonists by the effect of κ receptors could cause decrease of carbohydrate to fat ratio intake in rats (23). However, in our study with the inclusion of fat intake, BMI, and other confounders, a lower level of total cholesterol was seen in opium users.
The importance of serum lipid pro le is known as risk factor of cardiovascular diseases. Lipids pro le is one of the most important risks of metabolic syndrome and 10 years risk of cardiovascular disease. So, it is necessary to notice the correlation of opium consumption and serum lipids due to cut points that are known as hyperlipidemia in the clinic. Considering the cut point of abnormal level for serum lipids with the inclusion of other variables and confounders in the correlation of opium and lipid pro le, we found that opium usage was protective for increasing the level of total cholesterol and LDL to an abnormal cut point, but not for TG and HDL. Marmor M et al showed that usage of opium or morphine could have a protective effect against cardiovascular diseases (16), which is aligned with our results. But in contrast, many studies showed that opium addiction is correlated with cardiovascular diseases (24)(25)(26)(27)(28), and usage of opium increase the risk of death with several causes such as circulatory diseases (29). Contradiction in results could be due to the variation in method, dosage, and duration of consumption of opium in different studies.
Maybe with more studies, the level of opium consumption due to the effect of it on lipid pro le would be de ned as what has been done for harmful alcohol dosage.
As the strength of our study, we can mention the elimination of many confounding factors including medication, fat intake, BMI, and physical activity. The study is a population base in a large sample of people. Also, we used one type of device and a single laboratory to measure the amount of blood lipids of all participants.
One of the limitations of our study is that the cause and effect relation between opium and lipid pro le could not be shown, because of the type of study that is a cross sectional. It seems to be needed the assessment of this relation in longitudinal studies for detecting causality with consideration of dose and duration of consumption.

Conclusion
Lower levels of total cholesterol and HDL-C was seen in opium users but with consideration of abnormal cut point for lipid pro les, opium users had a normal level of LDL and total cholesterol in comparison with non-users who had abnormal levels. Despite our results, opium usage is not recommended for a decrease in lipid pro le and risk of heart disease because opium has known side effects on many organs and causes other non-communicable diseases such as cancers.

Declarations
Ethics approval and consent to participate: The study protocol was approved by National and Regional Ethics Committee of FUMS (code: IR.FUMS.REC.1396.234) and Research Board of Fasa University of medical Sciences (code: 94153). A written and informed consent was obtained from each participant to enter the rst phase of cohort study.
Availability of data and materials section: The datasets were analyzed during the study are available from the corresponding author on reasonable request.

Consent for Publication:
Not applicable Con ict of interests: Authors have no competing interest to declare. Funding: The study was funded by Fasa University of Medical Sciences (Grant # 94153).

Authors' contributions:
Aided in study conceptualization. aided in study design. aided in statistical analysis of data. aided in interpretation of study results. aided preparation of nal draft of manuscript. All Authors approved the nal form of the manuscript.