Thursday, November 5, 2015

Drugs-Related Death Soon After Hospital-Discharge among Drug Treatment Clients in Scotland: Record Linkage, Validation, and Investigation of Risk-Factors

We validate that the 28 days after hospital-discharge are high-risk for drugs-related death (DRD) among drug users in Scotland and investigate key risk-factors for DRDs soon after hospital-discharge. 

Using data from an anonymous linkage of hospitalisation and death records to the Scottish Drugs Misuse Database (SDMD), including over 98,000 individuals registered for drug treatment during 1 April 1996 to 31 March 2010 with 705,538 person-years, 173,107 hospital-stays, and 2,523 DRDs. Time-at-risk of DRD was categorised as: during hospitalization, within 28 days, 29–90 days, 91 days–1 year, >1 year since most recent hospital discharge versus ‘never admitted’. 

Factors of interest were: having ever injected, misuse of alcohol, length of hospital-stay (0–1 versus 2+ days), and main discharge-diagnosis. We confirm SDMD clients’ high DRD-rate soon after hospital-discharge in 2006–2010. DRD-rate in the 28 days after hospital-discharge did not vary by length of hospital-stay but was significantly higher for clients who had ever-injected versus otherwise. 

Three leading discharge-diagnoses accounted for only 150/290 DRDs in the 28 days after hospital-discharge, but ever-injectors for 222/290. Hospital-discharge remains a period of increased DRD-vulnerability in 2006–2010, as in 1996–2006, especially for those with a history of injecting.

...Our key confirmatory finding is that DRD-rates by time since most recent hospitalization remained significantly higher in the 28 days after hospital-discharge than at subsequent times post-discharge (with and without covariate adjustment). The SDMD cohort’s DRD-rate while hospitalized had decreased in 2006–2010, but absolute DRD-risks soon after hospital-discharge remained similar across both periods.

New SDMD registrations in the validation period of 2006–2010 were different from those in the earlier registration period in important respects: a higher proportion of 2006–2010 registered clients were 35 years of age or older at registration than among clients whose first SDMD registration was in 1996–2006, and a higher proportion reported never having injected. This suggests that Scottish drug users are not only ageing but that newer clients are less likely to have been initiated into injecting.

The study disputed our hypothesis that individuals who are hospitalized for a longer time (at least overnight) may be at greater DRD-risk post-discharge due to loss of tolerance. However, the duration of hospital-stay was a highly skewed variable; with a few individuals experiencing very long (several months) periods. There was insufficient statistical power to properly investigate the effect of short versus long stay lengths. A further subdivision of duration of hospital-stay as 0–1 day, 2–6 days and 7+ days (results not shown) also showed no difference between stays of less than versus greater than one week.

The influence of main discharge-diagnosis on subsequent DRD-risk was also analyzed by grouping the codes into pre-specified categories as used previously by Merrall et al. [4]. We needed to consider the entire SDMD cohort in order to have sufficient power per discharge-category and, even so, only two main discharge-diagnoses exceeded 30 DRDs within 28 days after hospital-discharge. These two discharge-categories were drug-related morbidity and mental and behavioral disorders excluding psychoactive substance misuse. Even together with diseases of the respiratory system, these top three DRD-risk discharge-categories accounted for only 52% (150/290) DRDs in the 28 days after hospital-discharge.

By contrast, behavioral risk-factors were far more discriminatory with ever injecting drug use accounting for the vast majority (77%: 222/290) of DRDs in the 28 days after discharge. This finding gives added focus to Scotland’s public health policy to make take-home naloxone (opiate antagonist) readily available, as well as training in its administration, not only in prisons and at drug treatment agencies but also at discharge from hospital, see [22] and [23]. Moreover, our new results suggest how hospital doctors can best target their harm reduction response [24]–not ineffectually according to patients’ length of hospital-stay, nor too narrowly by concentrating on a few main discharge-diagnoses, but highly efficiently by focusing on those who have ever injected. For ever injecting drug users, we note that one DRD in the 28 days after hospital-discharge per 400 discharges is about half their estimated DRD-risk in the 28 days after prison-release [25].

For the SDMD cohort of over 98,000 drug treatment clients in Scotland, we have confirmed that a high DRD risk soon after hospital-discharge applies in 2006–2010 as it did in 1996–2006 [14]. Length of hospital-stay had no effect on DRD-rate, discharge-diagnosis had an effect (as did reported misuse of alcohol) but neither was as discriminatory as the behavioral risk-factor of having ever injected.

Full article at: http://goo.gl/zRYOtN

By: 
Simon R. White, Sheila M. Bird
Medical Research Council Biostatistics Unit, Cambridge Institute of Public Health, Cambridge, United Kingdom

Elizabeth L. C. Merrall
Novartis Pharam BV, Novartis Vaccines & Diagnostics, Hullenbergweg 83–85, 1101 CL Amsterdam, Netherlands

Sharon J. Hutchinson
Health Protection Scotland, Glasgow, G3 7LN, Scotland, United Kingdom
  




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