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Table 1 Characteristics of the included studies by type of study and publication year

From: The reliability of suicide statistics: a systematic review

Study Publication-year Study period Area studied Population Cause and manner of death studied Method of sampling Number of cases(n) Results
Re-evaluation studies
Tsung-Hsueh, Lu et al. [37] 2006 1.1-31.12.2002 Taiwan (nationwide) All S, U Re-evaluated DC 3993 Fair quality of mode of death certification (MOD).
Carr J.R. et al. [36] 2004 1998-1999 USA (nationwide) US Military A*, U, H and deaths occurred within 30 days of retirement Re-evaluated DC, AR, TR, CR, MJ and investigative agency reports 1844 Concluded 21% underestimation.
         Found 17% underreporting, and additional 4% of deaths that were suspicious for suicide.
Ahlm, K. et al. [33] 2001 1999 Sweden (nationwide) All Traffic deaths Re-evaluated AR, DC, MJ and PR 580 ¶ 1.5% under-reporting.
         Found 3% (18 of 580) suicides among the officially registered accidental traffic deaths.
Sampson, H.M. and Rutty, G.N [31] 1999 1992-1997 South Yorkshire (West), England All S, OV Re-evaluated MJ, AR, and SN 295 Official national data may under-report the annual suicide rate by over 20%.
Ohberg, A. et al. [30] 1998 1.4.1987 - 31.3.1988 Finland (nationwide) All U Re-evaluated MJ and psychological autopsies. 139 Undetermined deaths resembled suicides and appeared to reduce the suicide rate by 10%
Connolly, J.F. and Cullen, A [28] 1995 1978-1992 County Mayo, Ireland All S, A**, U Re-evaluated DC, MJ 220 35% deaths were miscoded (n = 56) or unregistered (n = 16).
O'Donnell, I. and Farmer, R [29] 1995 A 5-year study period London (England) All S (deaths on the London Underground railway system) Re-evaluated. Records from LUL and the British Transport Police. Prospective design 242 Substantial underestimation of the true number of suicides.
         Verdicts other than suicide were returned on 25% and 50% of the women and men, respectively.
Scott, K.W.M [26] 1994 1976-1990 The borough of Wolverhampton (250.566) (England) All S Re-evaluated AR 394 ¶¶ 69% under-reporting.
         Estimated suicide rate of 10.5/100,000 per year. The official suicide rate were 6.2/100 000 per year. The coroners only reflected 59% of the probable true suicide rate.
Allebeck, P. et al. [24] 1991 1969-1983 Sweden (nationwide) Males conscripted for military service in 1969-70 CO, S, U, TD Re-evaluated DC, PR, MJ, TR and AR in a cohort of 50.465 322 High accuracy. Findings indicate an underreporting of suicide in cases of poisoning and other undetermined cases.
Rodriguez-Pulido, F. et al. [23] 1991 1977-1983 Canary Islands (Spain) All VD, ND Re-evaluated AR, SN, TE and JP 775 ¶¶ 104% under-reporting.
         Lack of validity and reliability of official figures of suicide. Recorded 8.1/100,000 suicides per year. The official published statistics recorded 3.98/100,000 per year for the same period. This represents 49% of which was found in this study.
Walsh, D.et al. [22] 1990 1978-1987 County Kildare, County Dublin and Dublin city (Ireland) All S, A, U Re-evaluated CR - ¶¶ 5% under-reporting.
         Reflecting the suicide rate accurately.
         Estimated 5.9/100,000 suicides per year. The official suicide rate were 5.6/100,000.
Huusko, R. and Hirvonen, J [20] 1988 1981 Oulu, Finland All S, A, U Re-evaluated PR, AR and MJ 283 The official figure for suicides could be as much as 18.9% too low.
Ekeberg, Ø. et al. [17] 1985 24.5.1978 - 26.4.1981 Norway (except Hordaland and Sogn og fjordane) All DI, D Re-evaluated AR 210 Underregistration of 10%
Malla, A. and Hoenig, J [16] 1983 1974-1978 Newfoundland (Canada) All S, CO Re-evaluated DC and AR 104 ¶¶ 12% under-reporting.
         Study suicide rate of 4.25/100,000 suicides per year, compared to the official rate of 3.8/100,000 per year.
Clarke-Finnegan, M. and Fahy, T. J [15] 1983 1978 Galway, Ireland All All deaths except natural deaths and TD Re-evaluated AR 410 ¶¶ 126% under-reporting.
         A minimum true rate of suicide was 13.1/100,000. The officially reported suicide rate was 5.8/100,000.
De Faire, U. et al. [13] 1976 1961-1973 Sweden (nationwide) Twins born in 1901-1925 All deaths Cohort of twins. Re-evaluated MJ, AR and PR 1156 Mortality data on suicide are fairly valid for use in epidemiological studies and mortality statistics with regard to suicides.
McCarthy, P. D. and Walsh, D [11] 1975 1964-1968 Dublin (Ireland) All All deaths investigated by Dublin city and county coroners Re-evaluated CR, MJ 210 ¶¶ 279% under-reporting.
         Official suicide rate of 1.4 per 100,000 and study-rate of 5.3 per 100,000.
Ovenstone, I.M.K [9] 1973 Oct.1969 - March 1971 Edinburgh (Scotland) All S, A, U and gas poisonings Re-evaluated MJ 214 Suicide rate was underestimated by approximately 50% by the Crown Counsel.
         The Crown counsel under-reporting suicide by 40.6% and the Scottish Registrar General 32%.
Litman, R.E. et al. [8] 1963 1959-1960 Los Angeles County All Equivocal suicides Re-evaluated PR, AR and interviewed survivors of the deceased. 100 Significant underreporting.
Combined re-evaluation and registry studies
Cantor, C. et al. [32] 2001 1990-1995 Queensland, Australia All Suicide beyond no reasonable doubt, probable and possible suicide Registry study and re-evaluated PR and AR 2728 5.5% more suicides registered in QSR than the official ABS count for the period.
         141 of the deaths coded as probable/possible suicides (675) by the QSR were rejected as being deaths other than suicide - usually accidental overdoses.
Thorslund, J et al. [21] 1989 1977-1986 Greenland All S, CO Registry study and Re-evaluated DC and PR 442 The official statistics are generally reliable.
Registry studies
Elnour, A.A. and Harrison, J [38] 2009 July 2000 - the end of 2005 Australia (nationwide) All S Registry study 12786 About 8% underestimation
Lahti, R.A. and Vuori, E [35] 2003 1997 Finland (nationwide) All DPD; A, S, U Registry study 500 Fairly good agreement. 98.5% agreement
Lindeman S.M. et al. [27] 1995 1986-1991 Finland (nationwide) All S, U, A*** Registry study 17 412 Reliable enough. 97% coverage.
Van de Voorde, H. et al. [25] 1993 1981-1984 Leuven (Belgium) All S Registry study 323 Incidence reporting bias of 4-8%.
         311 suicides found in one registry (PPO) and 323 suicides in the other registry (NIS).
Gary Hlady, W. and Middaugh, J.P [19] 1988 1983-1984 Alaska All S Registry study 195 Severely under-recorded suicides.
Marshall, D.L. and Soule, S [18] 1988 1979-1984 49 predominantly Native villages in southwest Alaska All VD; S, A, U, H Registry study 220 ¶¶405% under-reporting.
         Native suicide rate 36.9/100,000 (n = 38), compared to official suicide rate 7.3/100,000 (n = 5).
"Other re-evaluation studies"
Joseph, A. et al. [34] 2003 1994-1999 Kaniyambadi region, southern India All - Verbal autopsies - Mean suicide rate was 95.2/100,000 (range 83.7-106.3/100,000) - nine times the national average
Warshauer, M.E. and Monk, M [14] 1978 1968-1970 An area of New York City; East Harlem in Manhattan and three districts in the South Bronx. (USA) All S, "assigned" suicide Comparing published Health Department suicide rates with medical examiner records - Suicides among the black population were underestimated by 80% and those among whites by 42%. Suicide rates were greatly affected by the change in revision of the ICD.
Atkinson, M.W. et al. [10] 1975 - England and Denmark (nationwide) All Probable suicide Compared suicide ascertainment procedure between Denmark and England. 40 Danes consistently report more suicides than do the English coroners
Ross, O. and Kreitman, N [12] 1975 - England, Wales, Scotland (nationwide) All S, U, OV A two-way exchange of case records 264 The results strongly suggest that the two sets of officials share roughly the same criteria.
  1. A accident, AD all deaths, AR autopsy-/forensic-/post-mortem reports, CO controversial/unclear/no cause of death reported, CR coroner/medical examination records, D drowning, DC death certificates/report, DI deaths from intoxication, DPD drug poisoning deaths, H: homicide, JP judicial proceedings, MJ medical-/hospital journal/-report, ND natural death where insufficient medical information exists to permit the issuing of a death certificate stating that the cause of death was a natural one. OV open verdict, PR police reports, S suicide, SN suicide note, TE testimonies of relatives and witnesses, TD traffic deaths, TR toxicology reports, U undetermined, VD violent deaths, A* accidents by handgun, overdose, asphyxia, drowning and falling. A** road traffic accidents, fires in domestic dwellings and drownings were excluded. A*** motor vehicle accident, drowning, poisoning
  2. ¶ The authors have calculated the under-reporting: Found 18 "new suicides", total 1219 suicide and suicide rate 13.76/100,000 in Sweden in 1999 (data from Socialstyrelsen)
  3. ¶¶ ("study suicide rate" - official suicide rate)/official suicide rate