Burden,Risk Factors,and Knowledge of Non-fatal Opioid Overdose Among Injectable Drug Users: A Cross-sectional Study

Abstract

Background:

Opioid overdose is a significant public health problem among injectable drug users (IDUs), with non-fatal overdoses being a strong predictor of fatal overdoses. This study aimed to evaluate the burden, risk factors, and awareness related to non-fatal overdose among IDUs in Kolkata, India.

Methods:

This cross-sectional study was conducted from September 2023 to March 2025 at two opioid substitution therapy centers and two government hospitals in Kolkata. A total of 331 IDUs diagnosed with opioid use disorders participated. Data were collected through face-to-face interviews using a structured questionnaire assessing socio-demographics, substance use, overdose risk factors, and knowledge of overdose management. Descriptive statistics and regression analysis were employed.

Results:

A total of 331 IDUs were included. Among them, 73% used heroin, and 72.3% used buprenorphine. Major risk factors were sudden increases in heroin dosage (88.1%), injecting alone (83.8%), and sharing syringes (82.5%). Additionally, 24.1% reported a history of incarceration. Only 55.5% knew about calling an ambulance during an overdose, while 96.3% were aware that higher doses increase overdose risk. None were aware of naloxone use. Most participants (77.4%) expressed the need for more training on overdose management, while 88.7% feared aggression from overdose victims when administering naloxone. Attitude showed a protective trend, while knowledge and cumulative risk scores were not significantly associated with overdose in regression analysis.

Conclusion:

The findings underscore the need for comprehensive overdose prevention programs, including naloxone distribution and training and community-based education to address knowledge gaps and reduce opioid overdose mortality among IDUs in Kolkata.

Keywords

Inject opioids opioid substitution therapy (OST)overdose

Key Messages

This study aimed to evaluate the burden, risk factors, and awareness related to non-fatal overdose among injectable drug users (IDUs).

Among IDUs, 73% used heroin, and 72.3% used buprenorphine. Key overdose risks included dose surges (88.1%), injecting alone (83.8%), and syringe sharing (82.5%). Naloxone awareness was absent, and 77.4% sought overdose training. Only 55.5% knew to call an ambulance; 88.7% feared aggression during overdose response.

Substance overdose caused by drugs is responsible for nearly a third of drug-related fatalities worldwide,¹ and its contribution to India’s health problems cannot be ignored. The prevalence of drug use disorders in India, according to the National Mental Health Survey, stands at 0.6%.² There has been a considerable increase in illegal use of opioids, from 0.7% in 2004 to more than 2% in 2019.³ Among injectable drug users (IDUs), rates of opioid overdose remain markedly elevated, at almost 70%.⁴ Death due to heroin injection is frequently secondary to opioid overdose, with over half of all such deaths.⁵ Non-fatal overdose episodes are believed to be good indicators of future fatal overdoses among IDUs.⁶ Despite the increased risk, most people in this group have a general lack of knowledge regarding the instances of overdose and prevention.^7,8

India’s cultural variation also affects drug use behavior geographically. A study conducted in southern India found that opioid overdose was one of the most common causes of death among IDUs.⁹ On the other hand, research from northern India not only found a high prevalence of non-fatal overdose and its associated risk factors but also highlighted the apathetic attitudes and poor understanding of users regarding the management of overdose.¹⁰ The report of the Ministry of Social Justice and Empowerment, Government of India, mentions that West Bengal stands among the top ten states on the number of people requiring assistance for opioid-use-related problems.³ This reflects the alarming overdose rate witnessed in the state and highlights the critical need for immediate intervention and support services. Hence, the objective of the present study was to assess the burden, risk factors, and awareness of non-fatal opioid overdose among IDUs in Kolkata, India.

Methods

Study Design and Setting

The current research employed a cross-sectional design and was carried out at opioid substitution therapy (OST) centers of a non-governmental organization (NGO) (The Calcutta Samaritans) and the outpatient Department of Psychiatry in three government hospitals [Calcutta National Medical College and Hospital, Kolkata, India (OST center); RG Kar Medical College and Hospital, Kolkata, India; and Institute of Post Graduate Medical Education and Research and SSKM Hospital] in Kolkata, India, between September 2023 and March 2025. The centers offer services, such as buprenorphine for OST, counseling, and HIV treatment.

Study Population

All registered IDUs diagnosed with opioid use disorders who visited any one of the four study sites during the study period were included and interviewed.

Variables

A pre-designed and pilot-tested questionnaire was used for face-to-face interviews. Information about socio-demographic characteristics, medical and psychiatric comorbidities, opioid and substance use, known risk factors of opioid overdose,¹⁰ knowledge related to opioid overdose (Opioid Overdose Knowledge Scale),¹¹ attitude related to opioid overdose (Opioid Overdose Attitude Scale¹¹), and details of opioid overdose in the preceding year were collected. Data on substances used during overdose episodes were collected. The Opioid Overdose Knowledge Scale¹¹ and Opioid Overdose Attitude Scale¹¹ assess knowledge and attitudes toward opioid overdose and naloxone use. Previous studies have suggested that these scales are acceptable to a good range of internal consistency (Cronbach’s alpha values, 0.72 to 0.90). We translated the tools into Bengali using standard WHO forward-backwards translation methods, followed by expert review and pilot testing. In our sample, the internal consistency was acceptable.

A panel of three subject matter experts (addiction psychiatrist, public health researcher, and clinical pharmacologist) reviewed the initial draft for content validity and cultural appropriateness. The revised version was pilot-tested on 20 IDUs to ensure clarity and relevance. Feedback was incorporated to finalize the tool.

Sample Size Calculation

As building a sample frame and recruiting participants with opioid dependence was not straightforward,¹² registered IDUs who visited any of the four study sites during the data collection period were recruited. Hence, we utilized a complete enumeration approach instead of a random sampling technique.

Statistical Analysis

The categorical data were presented in proportions. The Kolmogorov–Smirnov test assessed the distribution of the continuous data. Descriptive statistics like proportion or mean were used to represent the data related to socio-demographic characteristics, medical and psychiatric comorbidities, opioid and substance use, risk factors of opioid overdose, knowledge and attitude related to opioid overdose, and details of opioid overdose. A cumulative risk score (range: 0–5) was computed for each participant based on five high-risk behaviors: sharing syringes, injecting when alone, sudden increase in dose, polydrug use, and housing instability. A multivariate logistic regression was performed to assess the independent associations of knowledge score, attitude score, and cumulative risk score with overdose history. All analyses were conducted using SPSS software version 22 (IBM Corp., Armonk, NY).

Results

Socio-demographic Characteristics of the Study Participants

A total of 331 IDUs were included in the study. The mean age was 25.1 ± 4.8 years, with most participants aged between 18 and 25 (54.8%). Most were male (97%), and 62.7% were never married. About half of the participants (49.8%) were unemployed, while 40% were daily-wage laborers. More than half (59.1%) reported a family history of drug use. Most participants (81.1%) lived in households with more than five members, and 40% were illiterate. The demographic characteristics of the study participants are enumerated in Table 1. The most commonly used opioids were heroin (73%) and buprenorphine (72.3%). Other common substance use (diazepam, promethazine, and pheniramine), along with smoking (76.9%) and alcohol (66.3%), was prevalent among participants. Most participants reported using heroin in doses exceeding 300–500 mg per injection, often combined with other central nervous system depressants. Common co-used substances included promethazine, diazepam, pheniramine, alcohol, buprenorphine, tramadol, and codeine. A total of eight patients were admitted through the casualty department for opioid overdose.

Table 1.

Demographic Characteristics of the Study Participants (n = 331).

Parameters		Results (%)
Age (years)	<18	70 (21.1%)
	18–25	181 (54.8)
	>25	80 (24.1)
Male (%)		321 (97)
Marital status (%)	Never married	208 (62.7)
	Presently married	110 (33.3)
	Divorced/separated/widow	13 (4)
Employment status (%)	Unemployed	165 (49.8)
	Daily-wage labor	132 (40)
	Service	19 (5.6)
	Business	15 (4.6)
Family history of drug use by at least one member of the family (%)		196 (59.1)
No. of members staying at the same house (%)	≤5	62 (18.9)
No. of members staying at the same house (%)	>5	269 (81.1)
The educational level of the patient (%)	Illiterate	132 (40)
	Primary school	149 (44.8)
	Secondary school	44 (13.2)
	Graduation and above	7 (2)
Occupation of the head of the family (%)	Unemployed	110 (33.3)
	Daily-wage labor	208 (62.8)
	Service	8 (2.3)
	Business	5 (1.6)
Polygamous sexual practices (%)		292 (88.1)
Details of opioid use (%)	Heroin	241 (73)
	Buprenorphine	239 (72.3)
	Morphine	92 (27.7)
	Pethidine	86 (26.1)
	Hydrocodone	67 (20.1)
	Codeine	64 (19.5)
	Tramadol	49 (14.9)
	Fentanyl	33 (10)
Other common addictions (%)	Smoking	255 (76.9)
	Alcohol	220 (66.3)
	Cannabis	108 (32.7)
Total per capita family income/month (%)	<₹5,000	232 (70)
Total per capita family income/month (%)	≥₹5,000	99 (30)
Average monthly expense on drugs (%)	<₹6,000	222 (67)
Average monthly expense on drugs (%)	≥₹6,000	109 (33)
Drug-related arrests and incarceration in the last 1 year (%)	0	214 (64.7)
	1–3	80 (24.1)
	>3	37 (11.2)
Status of concomitant viral infections (%)	Human immunodeficiency virus	25 (7.6)
	Hepatitis B virus	20 (6)
	Hepatitis C virus	13 (4)
Common medical comorbidity (%)	Hypertension	27 (8.2)
	Diabetes	19 (5.6)
	Chronic obstructive pulmonary disease	9 (2.6)
	Coronary artery disease	2 (0.7)
Common psychiatric comorbidity (%)	Anxiety	20 (5.9)
	Depression	27 (8.2)
	Somatoform disorder	15 (4.6)

₹: Indian rupees.

Risk Factors for Opioid Overdose

Table 2 presents the identified risk factors for opioid overdose among the study participants. A significant majority reported a sudden increase in the dose of heroin used for injecting in the last year (88.1%) and in the last three months (77.2%). About 83.8% injected opioids alone in the past year, and 74.7% in the last three months. Sharing of syringes or other injection paraphernalia was reported by 82.5% in the last year and 81.1% in the last three months. Many participants had been in jail in the past year (24.1%) and the last three months (18.5%). Other risk factors, such as switching opioids, using multiple opioids together, and consuming alcohol or benzodiazepines while injecting opioids, were also noted.

Table 2.

Risk Factors for Opioid Overdose Among the Study Participants (n = 331).

Questions	In the Last Year (%)	In the Last Three Months (%)
There is a sudden increase in the dose of heroin used for injecting	292 (88.1)	256 (77.2)
Injected opioids when one else is around	277 (83.8)	245 (74.7)
Shared syringes or other injection paraphernalia while injecting opioids	273(82.5)	269(81.1)
Abstinent from opioids	135 (40.9)	111 (33.7)
Have been in jail	80 (24.1)	61 (18.5)
Abruptly switched from one opioid to another	37 (11.2)	27 (8.2)
Living on the streets or lacking permanent housing	76(23.1)	71 (21.4)
Using multiple opioids by mixing/taking one after another	61 (18.5)	55 (16.5)
Using alcohol while injecting opioids or within 30 minutes before or after injection	70 (21.1)	64 (19.5)
Using benzodiazepines orally while injecting or within 30 minutes of drug use	47 (14.2)	43 (12.9)
Injected quickly out of fear of police/other people	7 (2)	3 (1)
Have received naltrexone for treatment of opioid dependence	0 (0)	0 (0)

The mean knowledge score was 10.3 ± 3.2, and the mean attitude score was 8.1 ± 2.4. In the multivariate logistic regression model, none of the predictors were statistically significant; however, the attitude score showed a protective trend against overdose (adjusted odds ratio: 0.92; 95% confidence interval: 0.81–1.03; p = .14). The cumulative risk score demonstrated a mild positive association with overdose risk (adjusted odds ratio: 1.09; 95% confidence interval: 0.83–1.43; p = .55), while the knowledge score was not significantly associated with overdose (adjusted odds ratio: 1.01; 95% confidence interval: 0.93–1.09; p = .85).

Knowledge About Opioid Overdose

The knowledge of participants regarding opioid overdose was assessed using the Opioid Overdose Knowledge Scale (Table 3). Most of the respondents stated that the risk of overdose was higher with the consumption of greater doses of heroin (96.3%) when consumption shifted from smoking to injecting (92.7%) and when heroin was combined with other substances, including alcohol (86.4%). However, knowledge about managing an overdose was limited, with only 55.5% knowing that calling an ambulance is a necessary step. None of the participants knew how to administer naloxone or its effects and benefits.

Table 3.

Response of the Study Participants as Per the Opioid Overdose Knowledge Scale* (n = 331).

Domains	Number of Correct Responders (%)
Which of the following factors increases the risk of a heroin (opioid) overdose?
Taking larger-than-usual doses of heroin	319 (96.3)
Switching from smoking to injecting heroin	307 (92.7)
Using heroin with other substances, such as alcohol or sleeping pills	286 (86.4)
Increase in heroin purity	317 (95.7)
Using heroin again after not having used it for a while	261 (78.7)
Using heroin when no one else is present around	147 (44.5)
A long history of heroin use	230 (69.4)
Using heroin again soon after release from prison	264 (79.7)
Using heroin again after a detoxification treatment	218 (65.8)
Which of the following are indicators of an opioid overdose?
Slow or shallow breathing	147 (44.5)
Lips, hands, or feet turning blue	133 (40.2)
Loss of consciousness	307 (92.7)
Unresponsive	330 (99.7)
Deep snoring	16 (5)
Very small pupils	23 (7)
Which of the following should be done when managing a heroin (opioid) overdose?
Call an ambulance	184 (55.5)
Stay with the person until an ambulance arrives	207 (62.5)
Give mouth-to-mouth resuscitation	59 (18)
Place the person in the recovery position (on their side with mouth clear)	78 (23.6)
Give naloxone (opioid overdose antidote)	0 (0)
Check for breathing	307 (92.7)
Check for blocked airways (nose and mouth)	98 (29.6)
What is naloxone used for?
To reverse the effects of an opioid overdose (e.g., heroin, methadone)	0 (0)
How can naloxone be administered?
Into a muscle (intramuscular)	0 (0)
Into a vein (intravenous)	0 (0)
Under the skin (subcutaneous)	0 (0)
Where is the most recommended place for non-experts to administer naloxone?
Outside of thighs or upper arms	0 (0)
How long does naloxone take to start having an effect?
2–5 minutes	0 (0)
How long do the effects of naloxone last?
About 1 hour	0 (0)
Miscellaneous
If the first dose of naloxone has no effect, a second dose can be given	0 (0)
Someone can overdose again even after having received naloxone	0 (0)
The effect of naloxone is shorter than the effects of heroin and methadone	0 (0)
Naloxone can provoke withdrawal symptoms	0 (0)

^*Only correct options are presented.

Attitudes Toward Opioid Overdose Management

Table 4 shows the participants’ attitudes as assessed by the Opioid Overdose Attitudes Scale. While most participants agreed (88.3%) that they had enough information about managing an overdose, 77.4% expressed the need for more training. There was a significant fear of administering naloxone due to potential aggression from the overdosed person (88.7%). Additionally, 99% of participants were reluctant to use naloxone for fear of causing withdrawal symptoms.

Table 4.

Response of the Study Participants as Per the Opioid Overdose Attitudes Scale (n = 331).

	Completely Agree (%)	Agree (%)	Unsure (%)	Disagree (%)	Completely Disagree (%)
Competencies to manage an opioid overdose
I already have enough information about how to manage an overdose	15 (4.6)	292 (88.3)	7 (2.1)	5 (1.4)	12 (3.5)
I am already able to inject naloxone into someone who has overdosed	–	–	–	–	331(100)
I would be able to check that someone who has overdosed was breathing properly	282 (85.1)	41 (12.4)	8 (2.5)	–	–
I am going to need more training before I would feel confident to help someone who has overdosed	256 (77.4)	58 (17.7)	–	14 (4.2)	2 (0.7)
I would be able to perform mouth-to-mouth resuscitation on someone who has overdosed	9 (2.8)	8 (2.5)	269 (81.3)	39 (11.7)	6 (1.8)
I would be able to perform chest compressions on someone who has overdosed	19 (5.6)	5 (1.4)	233 (70.4)	51 (15.5)	23 (7.1)
If someone overdoses, I will know what to do to help them	1 (0.3)	49 (14.9)	258 (78.1)	15 (4.6)	7 (2.1)
I would be able to place someone who has overdosed in the recovery position	1 (0.3)	11 (3.2)	291 (88)	20 (6)	8 (2.5)
I know very little about how to help someone who has overdosed	15 (4.6)	222 (67.1)	75 (22.6)	7 (2.1)	12 (3.5)
I would be able to deal effectively with an overdose	–	6 (1.8)	323 (98.6)	2 (0.7)	–
Concerns about managing an opioid overdose
I would be afraid of giving naloxone in case the person becomes aggressive afterward	294 (88.7)	37 (11.3)	–	–	–
I would be afraid of doing something wrong in an overdose situation.	–	13 (3.9)	305 (92.2)	7 (2.1)	6 (1.8)
I would be reluctant to use naloxone for fear of precipitating withdrawal symptoms.	–	4 (1.1)	327 (99)	–	–
I would be concerned about calling emergency services in case the police come around	23 (7.1)	281 (84.9)	7 (2.1)	8 (2.5)	12 (3.5)
If I tried to help someone who has overdosed, I might accidentally hurt them	27 (8.1)	53 (15.9)	193 (58.3)	53 (16)	6 (1.8)
I would feel safer if I knew that naloxone was around	–	–	331 (100)	–	–
I would be afraid of suffering a needle stick injury if I had to give someone a naloxone injection	–	14 (4.2)	317 (95.8)	–	–
Needles frighten me, and I would not be able to give someone an injection of naloxone.	–	12 (3.5)	319 (96.4)	–	–
Readiness to intervene in an opioid overdose
Everyone at risk of witnessing an overdose should be given a naloxone supply.	–	–	331 (100)	–	–
I could not just watch someone overdose, I would have to do something to help	282 (85.1)	41 (12.4)	8 (2.5)	–	–
If someone overdoses, I would call an ambulance, but I would not be willing to do anything else	94 (28.3)	102 (30.8)	65 (19.8)	28 (8.5)	42 (12.7)
Family and friends of drug users should be prepared to deal with an overdose	28 (8.5)	28 (8.5)	247 (74.5)	25 (7.4)	4 (1.1)
If I saw an overdose, I would panic and not be able to help	6 (1.8)	18 (5.3)	18 (5.3)	151 (45.6)	139 (39.3)
If I witnessed an overdose, I would call an ambulance straight away	91 (27.6)	104 (31.4)	64 (19.4)	27 (8.1)	44 (12.5)
I would stay with the overdose victim until help arrives	20 (6)	4 (1.1)	8 (2.5)	156 (46.7)	144 (43.4)
If I saw an overdose, I would feel nervous, but I would still take the necessary actions	140 (42.4)	152 (46)	35 (10.6)	2 (0.7)	1 (0.3)
I will do whatever is necessary to save someone’s life in an overdose situation	323 (97.5)	8 (2.5)	–	–	–
If someone overdoses, I want to be able to help them	288 (87)	37 (11.3)	6 (1.8)	–	–

Prevalence and Details of Opioid Overdose

Regarding opioid overdose, 85.1% of participants reported no episodes in their lifetime, and 91.7% reported no episodes in the last year. For those who had experienced an opioid overdose, heroin, buprenorphine, and morphine were the commonly involved opioids. The route of administration was primarily intravenous, and the clinical features included difficulty breathing and turning blue, followed by loss of consciousness. Informal caregivers mainly provided treatment with supportive management.

Discussion

This study provides a comprehensive assessment of the burden, risk factors, and awareness gaps concerning non-fatal opioid overdose among IDUs in Kolkata. According to our current knowledge, no previous research on this topic has been conducted among IDUs in Kolkata. The findings align with the existing literature on opioid use among IDUs globally and in India, highlighting several key areas that require urgent public health intervention.

The present study highlights a significant burden of opioid use among IDUs in Kolkata, with a high prevalence of heroin (73%) and buprenorphine (72.3%) use. These findings are consistent with the report on substance use by the Government of India that noted an increase in illicit opioid use in India, affecting around 8,50,000 IDUs nationwide.³ A similar study in north India also reported a high prevalence of opioid use, with 71% of participants using heroin as their primary injected opioid.¹⁰ The rate of non-fatal opioid overdose in this study was remarkably high, with 70% of participants reporting an overdose at some point. Similar kinds and types of patterns were seen in a northern Indian study, with 45% of the drug injectors reporting at least one lifetime history of opioid overdose and 25% reporting an overdose in the past year.¹⁰ The high prevalence of non-fatal opioid overdose underscores the need for targeted overdose prevention and management interventions among IDUs in India.

Our study identified several risk factors for opioid overdose, such as sudden increases in heroin dose (88.1%), injecting opioids when alone (83.8%), and sharing syringes (82.5%). High-risk drug combinations also significantly potentiate respiratory depression and contribute to the clinical severity of overdoses. These risk factors have been widely documented in previous studies. For instance, a previous study conducted in the United States identified similar risk factors among syringe exchange participants, including injecting alone and sharing injecting equipment, both of which increase overdose risk.¹³ Furthermore, the concurrent use of alcohol and other substances, such as benzodiazepines, reported by 21.1% and 14.2% of our participants, respectively, is known to amplify the risk of opioid overdose by depressing the central nervous system.^14,15 We also found that recently incarcerated individuals are at heightened overdose risk following a period of imprisonment due to decreased drug tolerance at release, as evidenced internationally and nationally. This highlights the need for targeted intervention for this high-risk group in the form of post-release harm reduction, education, and access to OST to reduce the risk of overdose.

International studies have consistently highlighted these risk behaviors as critical areas for intervention. A systematic review emphasized the importance of harm reduction services, such as supervised injection facilities, to reduce overdose risk by providing a safe environment where drug use is monitored and naloxone is readily available.¹⁶ In our context, establishing such facilities in urban centers like Kolkata could significantly mitigate the risk factors identified in this study. A primary concern identified in this study is the inadequate knowledge among IDUs about managing opioid overdose, particularly regarding naloxone use. None of the participants knew how to administer naloxone or its benefits, and only 55.5% recognized the need to call an ambulance during an overdose. This is consistent with findings from other studies in India, where no participant knew about naloxone use for overdose management.¹⁰ Similarly, another previous study found that IDUs in Los Angeles lacked adequate knowledge of overdose management, underscoring the need for targeted training programs.¹⁷

Naloxone is a life-saving opioid antagonist that can reverse the effects of overdose if administered promptly. Take-home naloxone programs have proven highly effective in reducing opioid overdose mortality in several countries. A previous study has demonstrated that naloxone training and distribution significantly improved knowledge and preparedness among IDUs, resulting in better outcomes in managing overdoses.¹⁸ Implementing similar programs in India, particularly in high-risk areas like Kolkata, could bridge the current knowledge gaps and reduce non-fatal opioid overdose rates. In a previous qualitative study on treatment utilization and overdose risk among opioid users in Kolkata, it was found that there was a significant lack of knowledge about naloxone, the antidote for opioid overdose, among individuals who used opioids, as well as the peer support workers who assisted them with the treatment.¹⁹ Participants in the interviews were not aware of naloxone—its availability or correct protocol for its use in the event of an opioid overdose. Some participants expressed curiosity and a desire to learn about naloxone, indicating a potential openness to education and training on overdose management. This gap in knowledge presents a critical barrier to effective overdose prevention. It underscores the need for targeted educational interventions to promote awareness and accessibility of naloxone in high-risk communities.¹⁹

Although knowledge about overdose was generally low among participants, our multivariate analysis showed that knowledge scores were not significantly associated with overdose history. This finding is consistent with previous literature, which suggests that knowledge alone may be insufficient to reduce high-risk behaviors among IDUs unless coupled with skill-building and behavioral interventions.^17,21 Interestingly, we observed that higher attitude scores were associated with lower odds of overdose, albeit not reaching statistical significance. This suggests that positive attitudes toward overdose management, such as willingness to intervene and confidence in response measures, may have a protective effect, as reported in earlier studies evaluating community training programs and naloxone distribution efforts.^16,18 Furthermore, the cumulative risk score, derived from five well-established behavioral risk factors, showed a mild positive association with overdose risk. While not statistically significant in this sample, the observed trend aligns with prior research that emphasizes the additive nature of overdose risk when multiple behaviors co-occur.^13,15 Future interventions may benefit from targeting these behavioral patterns collectively rather than in isolation, using integrated harm-reduction strategies.

In addition to knowledge gaps, our study revealed significant attitudinal barriers to effective overdose management. Despite 88.3% of participants believing they had enough information about managing an overdose, 77.4% expressed a need for more training. Fear of potential aggression from the overdose victim was reported by 88.7% of participants as a deterrent to administering naloxone. Findings from studies in other settings support these concerns. An earlier study noted that fear of police involvement and uncertainty about their ability to manage overdose situations prevented many veterans from using naloxone.²⁰ These findings underscore the need for community-based education programs addressing knowledge and attitudinal barriers. Educational interventions should focus on practical training in overdose response, including naloxone administration, and address the stigma and legal concerns associated with seeking help in overdose situations. Programs that engage IDUs, their families, and the broader community in overdose prevention can help build a more supportive environment for safe practices.^21,22

The high prevalence of opioid use, significant risk factors, and substantial knowledge and attitudinal barriers identified in this study have important implications for public health policy and practice in India. First, there is an urgent need for comprehensive overdose prevention programs that incorporate naloxone distribution, education, and harm reduction services. Most of the evidence from overdose prevention strategies that have been used in community settings around the United States and Europe indicates that these interventions can significantly reduce overdose-related morbidity and mortality.^7,16 Second, integrating harm reduction strategies, such as needle exchange programs and supervised injection sites, can provide safer environments for IDUs, reduce risky injection practices, and facilitate access to healthcare services.^17,21 These strategies have been successful in other countries and could be adapted to the Indian context with appropriate modifications to address local needs and legal frameworks.¹⁸

While this study provides valuable insights into the burden and risk factors of opioid overdose among IDUs in Kolkata, several limitations must be acknowledged. The cross-sectional design limits the ability to infer causality between identified risk factors and overdose events. Moreover, the study was conducted among IDUs registered at two OST centers and two government hospitals, which may introduce selection bias. Including a more diverse sample of IDUs, including those not engaged in treatment, could provide a more comprehensive understanding and generalizability of overdose risks in India. Future research should focus on longitudinal studies to evaluate the long-term impact of interventions on overdose rates and to identify factors that may influence changes in risk behaviors over time. Additionally, research on the effectiveness of community-based naloxone distribution and overdose prevention programs in India could provide valuable evidence to guide policy decisions.

Conclusion

The findings of this study highlight the urgent need for comprehensive overdose prevention programs targeting IDUs in Kolkata and other parts of India. Addressing knowledge and awareness gaps, reducing risk behaviors, and overcoming attitudinal barriers through targeted education, naloxone distribution, and harm reduction services are critical steps to reducing opioid overdose mortality. We found that attitude showed a protective trend, while knowledge and cumulative risk scores were not significantly associated with overdose in regression analysis. Our study also found a high degree of ignorance regarding naloxone among opioid users, further underscoring the need for targeted education campaigns for overdose response. By implementing evidence-based strategies, India can better support this vulnerable population and improve public health outcomes.

Supplemental Material

Supplemental material for this article available online.

Footnotes

Acknowledgements

We thank all peer educators, nurses, and staff of Calcutta Pavlov Hospital (Calcutta National Medical College) Hospital and from The Calcutta Samaritans, Kolkata, India.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Declaration Regarding the Use of Generative AI

None used.

Ethical Approval

The study protocol underwent review and approval by the relevant institutional ethics committees. Prior to participation, written informed consent was obtained from all study participants, including opioid users and peer educators. The confidentiality of both participants and the information gathered was rigorously maintained throughout the study process.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by the ICMR, New Delhi, India (extramural project file no. 5/4-5/3/2/Trauma-call/ Poisoning/2022/NCD-1).

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