Professional baseball players have lower mortality rates than the US general population, but whether this is true of foreign-born players is not known. Using data on ballplayers from six nations, we compare mortality rates with those of US players via standardized mortality ratios. After controlling for confounders, four countries had statistically insignificant SMRs while two nations had significantly elevated SMRs. In the two nations with elevated SMRs, low average ages at death and high crime rates suggest the increased mortality may be linked to violent crime. A full understanding of the causes of disparity in mortality will require further research

Robert J. Reynolds

Steven M. Day

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 GJMEDPH, Vol 1(4) July- August 2012  Page 38    Global Journal of Medicine and Public Health     www.gjmedph.org  Mortality of major league baseball players from Canada, Latin America, and the Caribbean Robert J. Reynolds*, Steven M. Day** *The University of Texas Health Science Center at Houston, School of Public Health Houston, TX,USA, **Mortality Research & Consulting Newport Beach, CA, USA  A B S T R A C T Professional baseball players have lower mortality rates than the US general population, but whether this is true of foreign-born players is not known. Using data on ballplayers from six nations, we compare mortality rates with those of US players via standardized mortality ratios. After  controlling  for  confounders,  four  countries  had statistically insignificant SMRs while two nations had significantly elevated SMRs. In the two nations with elevated SMRs, low average ages at death and high crime rates suggest the increased mortality may be linked to violent crime. A full understanding of the causes of disparity in mortality will require further research. Keywords: baseball, international, mortality, standardized mortality ratios, life expectancy  Corresponding Author: Robert J. Reynolds, The University of Texas Health Science Center at Houston, School of Public Health 1200 Pressler St. Houston, TX 77030, USA                    Funding: None         Conflict of interest: None     Introduction It  is  well-established  that  professional  athletes  live longer  than  matched  controls  in  the  general population.1-3 Major League Baseball (MLB) players in particular  have  been  studied  repeatedly  and  found  to have lower mortality rates at all ages and in nearly all decades of the 20th Century.1-2  Life expectancies also vary widely across nations. For example, as of 2009, the life expectancy at birth in the US  was  79  years.4  More  than  30  nations  had  life expectancies  greater  than  the  US,  and  the  life expectancy at birth of the nations of the world ranged from as low as 47 years to as high as 83 years.4  Though  played  only  in  the  US  and  Canada,  MLB  is truly  an  international  sport,  historically  comprising players  from  more  than  50  nations.  An  unanswered question  is  what  effect  playing  professional  sports  in the US may have on the mortality rates of athletes from other  countries.  Baseball  players  from  nations  with substantially  different  general  population  mortality rates  may  in  turn  be  subject  to  greater  or  lesser mortality  than  their  MLB  counterparts  from  the  US. Such  enduring  differences  would  suggest  that  the variation in international mortality may have more to do with  stable  characteristics  of  populations  (such  as genetics  or  macro-culture)  and  less  to  do  with modifiable  environmental,  political,  and  socio-economic factors (such as individual lifestyle or micro-culture).  It  is  also  possible  that  differences  in international  mortality  stem  almost  exclusively  from these  modifiable factors, in  which case, to the extent their  lives  are  made  homogeneous  with  lives  of  US-born citizens by the experience of playing in the Majors, baseball  players  from  other  nations  would  have essentially  equivalent  mortality  rates  to  players  from the US.  To investigate this question, we analyzed data from the six best-represented foreign nations in MLB: Canada, Cuba, Dominican Republic, Mexico, Puerto Rico, and Venezuela.  Methods Source  Data:  The  MLB  data  were  provided  by  the Baseball  Almanac  (www.baseball-almanac.com).  The Baseball  Almanac  is  a  complete  collection  of biographical and performance data for all Major League ballplayers  since  1871.  The  database  is  regularly updated  and  draws  on  the  work  of  the  Biographical Research  Committee  at  the  Society  for  American Baseball  Research.  Staffed  by  approximately  100 volunteers,  the  committee’s  purpose  is  to  maintain accurate biographical data on Major League ballplayers, including  date  and  place  of  birth  and  death.  The committee  researches  player  deaths  using  the  Social Security Death Index, news media reports, and contact with surviving family members.   GJMEDPH, Vol 1(4) July- August 2012  Page 39  From  the  biographical  portion  of  the  database  we extracted the date and place of birth, date of debut in the Majors, and date of death (where applicable) for all MLB players. From the performance data, we extracted the fielding positions and number of games played at those positions for each player.  Study Population: Our study population was the set of players  born  in  the  six  countries  of  interest,  who debuted in the Major Leagues between January 1, 1900 and December 31, 1999, and who were still alive as of January  1,  1950.  We  chose  this  period  because  the inclusion  of  players  from  other  nations  in  the  Major Leagues is a relatively new phenomenon with most of the six nations under study entering the Majors in the 1930s or later. Limiting the data to players alive as of 1950  and  later  provided  enough  information  to  draw meaningful conclusions for all six nations. In order to form  the  comparison  group  for  these  players,  we analogously selected all US-born players from the same period who were alive as of 1950.  The period of follow-up for each player was the time from  the  individual  player’s  debut  in  the  Majors  to either his date of death or the end of the study period, whichever came first. The starting date for players who debuted before 1950 was January 1, 1950. Players who died after December 31, 1999 were considered alive at the end of the study period for purposes of analysis.  In  accordance  with  Federal  Regulations  on  the protection of human subjects in medical research, this study was exempt from institutional review as all data used  here  are  publicly  available  and  no  contact  was attempted  or  made  with  study  subjects  during  the course of the study.  Causal  Model:  Our  causal  model  for  this  study  is shown in Figure 1 as a directed acyclic graph (DAG), drawn  using the DAGitty  software (www.dagitty.net). We have assumed a simple model in which there is a direct  effect  of  the  exposure  (national  origin)  on  the outcome (mortality). There is also an indirect effect of national origin on mortality by way of player position and an indirect effect of national origin on mortality by way of secular trend. According to this DAG, the effect of  both  secular  trend  and  player  position  must  be controlled in order to correctly estimate the direct effect of national origin on mortality.  To  control  for  secular  trend,  data  were  stratified  by decade. We chose to include secular trend in our causal model  because  previous  research  demonstrates  that mortality rates for US-born baseball players have fallen over  time.1-2  The  pathway  from  national  origin  to secular trend in the DAG reflects the idea that changes Figure 1.Causal model for the relationship between national  origin  and  mortality  for  Major  League Baseball players.    in  the  mortality  rates  over  time  may  be  different  for different  nations.  The  node  for  secular  trend  can  be thought of as a collection of unmeasured time-varying confounders. By controlling for these unmeasured time-varying confounders, we aim to increase the precision of our estimated effect of national origin on mortality.  We  also  controlled  for  fielding  position.  A  given player's position was defined to be the position at which the player played the greatest number of games during his career.   We  elected  to  include  player  position  in  our  causal model  because  each  fielding  position  demands  a slightly  different  set  of  physical  skills  resulting  in players  of  different  body  type,    athletic  ability,  and physical fitness demands (e.g., it is highly unlikely that a center fielder will be overweight, whereas a pitcher may  well  be).  If  fielding  positions  are  preferentially recruited from specific nations, this could confound the relationship between national origin and mortality.  Hypotheses:  We  hypothesized  that  mortality  rates  for ballplayers  from  a  given  nation  would  compare  with those  of  US  ballplayers  in  the  same  way  as  general population rates in the given nation compare with US general population rates. Therefore, based on the rank order  of  life  expectancies  published  by  the  World Health Organization4, we specifically hypothesized that players from Canada would have lower mortality rates than players from the US (SMR < 1.0), players from Cuba  and  Puerto  Rico  would  have  mortality  rates similar to US players (SMR ≈ 1.0), and players from the  remaining  nations  would  have  mortality  rates greater in magnitude than those of US players (SMR > 1.0). Statistical Methods:To compare mortality rates between each of the six nations and the US, we computed SMRs  GJMEDPH, Vol 1(4) July- August 2012  Page 40  and  95%  confidence  intervals,  controlling  for  age  in five-year intervals, and decade and player position as outlined above. The procedure was, in brief:  1.  We summed the person-years at risk and the number  of  deaths  for  all  players,  separately  by  age group, nation, player position, and decade. 2.  Next, we computed the mortality rates for the US players by dividing the number of observed deaths by the accrued person-years for each age group, player position, and decade. These age-, position-, and time-specific mortality rates were then used to calculate the expected numbers of deaths for the other nations.  3.  Within each age × position × time stratum, the expected  counts  of  deaths  for  the  six  nations  under study were the products of the mortality rates of the US players for a stratum and the accrued person-years of time at risk from each country for that stratum. 4.  The  observed  and  expected  counts  of  deaths were summed across strata for each nation. 5.  SMRs  were  calculated  as  the  ratio  of  the counts  of  observed  deaths  in  the  MLB  cohort  to  the expected number from step 4. 5.  Finally,  we  computed  95%  confidence intervals  around  the  SMR  by  assuming  the  observed counts of deaths derived from a Poisson distribution.  All analyses were completed using SAS version 9.1 and Microsoft Excel 2007.  Results And Discussion Table  1  displays  the  distribution  of  players,  person-years, and deaths by nations, as well as the mean age at death for each. The 917 players from the six nations under study contributed a total of 16,678.6 person-years of follow-up with a total of 118 deaths in the period. While the Dominican Republic had the  most non-US players  in  the  study,  the  most  non-US  person-years were accrued by Cuba, followed by Puerto Rico, and then the Dominican Republic. Canada and Cuba were nearly  tied  for  the  most  deaths  with  44  and  43, respectively,  and  in  distant  third  place  was  the Dominican Republic with 9 deaths.  Table 1. Player Data by Nation, 1950-1999. Nation  Players  Person-Years Deaths  Age at Death Mean (SD) Canada   119   2,748.2   43  72.1 (12.6) Cuba   136   4,325.9   44  67.4 (11.4) Dom Rep   280   3,275.5     9  41.9 (10.5) Mexico     81   1,512.1     7  60.1 (20.4) Puerto Rico  185   3,405.9     7  46.1 (14.6) Venezuela   116   1,411.0     8  44.3 (13.9) TOTALS   917  16,678.6  118  63.9 (16.4)  Figure  2  shows  the  SMRs  for  the  various  nations  in comparison  with  the  US.  The  square  points  for  each nation represent the point estimate for the SMR, and the lines  extending  to  the  left  and  right  from  the  points represent the 95% confidence intervals around the point estimates. Those bands which cross the dashed vertical line indicate that the SMR cannot be said to be different from  1.0  with  95%  confidence;  whereas,  any  bands which  do  not  cross  the  dashed  line  indicate  that  the SMR  can  be  said  to be  different  from  1.0  with  95% confidence.   Figure  2.  Standardized  mortality  ratios  and  95% confidence intervals for international Major League Baseball players, 1950-1999.    The  figure  shows  that  Canada,  Cuba,  Mexico,  and Puerto Rico all have SMR point estimates close to unity and confidence intervals that include 1.0. On the other hand, the Dominican Republic and Venezuela both have SMRs  well  above  1.0  with  confidence  intervals  that depart from unity.  The results of our analysis show that, after controlling for  age,  player  position,  and  decade,  the  number  of deaths  experienced  by  baseball  players  from  Canada, Cuba, Puerto Rico and Mexico are on par with those for players from the United States, while ballplayers from the Dominican Republic and Venezuela experienced a significantly greater number of deaths than expected.   For four of the six nations  under study, the effect of playing  Major  League  Baseball  appeared  to  be  a homogenizing  one:  once  these  players  were  removed from their nation of origin and given the same set of  GJMEDPH, Vol 1(4) July- August 2012  Page 41  circumstantial exposures as players from the US, their mortality experience was nearly identical. This would support  a  hypothesis  that  differences  in  mortality between  nations  are  largely  due  to  malleable  factors such  as  personal  income,  access  to  healthcare,  and lifestyle.   In contrast, the fact that the players from the Dominican Republic and Venezuela experienced significantly more deaths than expected was in keeping with our original hypotheses. This weighs in favor of the explanation that the differences in mortality between nations are due to immutable factors such as genetics and macro-cultural issues.  For  these  players,  there  was  no  effect  on mortality  of  coming  to  the  United  States  or  being  a Major League Baseball player.  The  causes  of  death  for  the  ballplayers  would  be  a useful  addition  to  this  study.  If  we  were  to  calculate SMRs  by  cause  of  death,  we  might  observe  that  the beneficial  effect  of  participation  in  Major  League Baseball  is  to  specifically  diminish  the  risk  of  death from natural causes while simultaneously increasing the risk  of  death  from  external  causes  (accidents  and violence). In nations such as the Dominican Republic and  Venezuela  –  where  violent  crime  is  rampant, especially that related to the kidnapping and murder of the wealthy5-6 – this added risk of death from external causes may outweigh any benefits from lower risk of natural  causes.  The  mean  ages  of  death  in  Table  1 suggest that this may indeed be the case: in Venezuela and the Dominican Republic the mean age of death is in the early 40s, in comparison to the low 60s for Mexico, high 60s for Cuba, and high 70s for Canada. (Puerto Rico, which also had a mean age of death in the mid-40s, did not exhibit a statistically significant difference in deaths; however, Puerto Rico is also not known for excessive  violence.)  In  most  of  the  Western  world,  a young average age at death is often associated with a high rate of death from external causes.  Regardless  of  the  true  effects  of  playing  MLB,  the results  of  this  study  strongly  suggest  that  the  stable characteristics  of  populations  and  the  modifiable characteristics of individuals may both contribute to the mortality rates of general populations, and thus account for  the  differences  between  nations.  Future  research focusing  on  the  causes  of  death  across  analogous cohorts  would  be  valuable,  especially  as  the  nation effect  could  be  then  treated  as  potentially multidimensional.  Such  detailed  analyses  would  help unravel  the  mysteries  of  mortality  rate  disparities, which may offer paths for improvement in survival in all nations.  Acknowledgements:  The authors wish to thank Sean Holtz, webmaster and owner of baseball-almanac.com for providing the data, Florizel Tucker for copyediting, and the reviewers and journal editors for thorough and insightful reviews. A previous version of this work was presented  in  poster  form  at  the  3rd  North  American Congress of Epidemiology, June 2011.  References  1.  Reynolds  RJ  and  Day  SM.  Life  expectancy  and comparative  mortality  of  Major  League  Baseball players,  1900-1999.  WebmedCentral  SPORTS MEDICINE 2012;3(5):WMC003380. 2.  Saint  Onge  JM,  Rogers  RG,  Krueger  PM (2008).Major  league  baseball  players'  life expectancies.  Social  Science  Quarterly,  89(3):817-30. 3.  Baron SL, Hein MJ, Lehman E, Gersic CM (2012). Body Mass Index, Playing Position, Race, and the Cardiovascular  Mortality  of  Retired  Professional Football  Players.  The  American  Journal  of Cardiology, 109:889-896. 4.  World  Health  Organization.  “Life  Expectancy  at Birth,  Both  Sexes,  2009.” <http://gamapserver.who.int/gho/interactive_charts/mbd/life_expectancy/atlas.html>  Accessed  15  July 2012. 5.  United  States  Department  of  State.  “Venezuela Country  Specific  Information.” <http://travel.state.gov/travel/cis_pa_tw/cis/cis_1059.html> Accessed 15 July 2012. 6.  United  States  Department  of  State.  “Dominican Republic  Country  Specific  Information.” <http://travel.state.gov/travel/cis_pa_tw/cis/cis_1103.html> Accessed 15 July 2012.        Access This Article Online Quick Response Code:   Website: www.gjmedph.org   

Mortality of major league baseball players from Canada, Latin America, and the Caribbean

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