Appendix Table 3.

Synthesis of studies found using the first search strategy focusing on HRI

Studies making use of administrative databases
Paper	Codes employed to identify HRI	Study period	Heat index	Administrative database	Association measure	Type of study	Lag time	Definition of heatwave employed
Adam-Poupart et al (2)	Can_Stand_Assoc_Standard Z795 07200-Effects of heat or light, 07210-Heat stroke, 07220-Heat syncope, 07280-Multiple effects of heat or light, 07290-Effects of heat or light (not elsewhere classified) including heat-related fatigue and edema	From May 1st to September 30th of each year between 1998 and 2010	Daily maximum temperature	Workers' Compensation Board (WCB) of Quebec.	IRR per 1°C increase	Incidence	0-1-2; moving average (01; 0-1-2)	N/A
Bonauto et al (13)	ICD-9 codes: 992.0—Heat stroke and sunstroke; 992.1—Heat syncope; 992.2—Heat cramps; 992.3—Heat exhaustion, anhydrotic; 992.4—Heat exhaustion due to salt depletion; 992.5—Heat exhaustion, unspecified; 992.6—Heat fatigue, transient; 992.7—Heat edema; 992.8—Other specified heat effects; or 992.9—Effects of heat and light, unspecified; and/or an ANSI Z16.2 type code 151 (Contact with general heat—atmosphere or environment)	January 1, 1995 and December 31, 2005	Maximum daily temperature	Workers' compensation insurance	N/A	Descriptive; Incidence rates	3 days	N/A
Fortune et al (33)	In ED records, a case of heat illness was defined on the basis of ICD-10-CA codes for conditions diagnosed as heatstroke, sunstroke, heat collapse, heat cramps, heat exhaustion, heat fatigue, heat edema or other effects of heat and light. Among lost time claims, a case of heat illness was defined by information describing the nature, event or source of injury.	January 2004 to December 2010	N/A	Emergency Department visits and Workplace Compensation Lost Time Claims	Proportionate morbidity ratio (PMR)	Incidence rates	N/A	N/A
Fortune et al (32)	(a) Heat-related Main or Other Problem listed: T57: Effects of heat and light X30: Exposure to excessive natural heat W92: Exposure to excessive heat of man-made origin	January 1, 2004 and December 31, 2010	Maximum daily T°	Emergency department, work-related, non-scheduled visits	Generalized Linear Mixed Model, with Bayesian inference	Ecologic time series analysis	The sum of the differences between temperature on the current day and that on the previous three days (Tlag3)	N/A
Fuhrmann et al (34)	ICD-9-CM code 992.x	2007-2011	Heat emergency response plan by National Weather Service (NWS). Apparent temperature.	Emergency Department Visits	Observed versus expected ED visits	??	N/A	At least one heat product must have been issued and verified across four or more NWS county warning areas in North Carolina for five or more consecutive days. A heat event was terminated if there was a lapse in these conditions for at least 5 days.
Garzon Villalba et al (37)	Incidents with a primary or secondary code that suggested a heat-related disorder (e.g., 0721-0724). EHI included acute health events related to heat such as heat stroke, heat syncope, and heat exhaustion.	May 2010-March 2011	WBGTmax	British Petroleum Workers' compensation database	IRR per 1°C above - WBGTmax 20	Incidence	1	N.A.
Gubernot et al (38)	A heat-related death is identified in CFOI as an exposure to environmental heat with the BLS Occupational Injury and Illness Classification System event/exposure code 321 and the nature code of 072	2000-2010	N/A	Census of Fatal Occupational Injuries (CFOI) database	Rate Ratios per state	Incidence	N/A	N/A
Harduar-Morano et al (42)	HRI (ICD-9-CM 992.0-992.9 and E900.0, E900.1, E900.9). Work relatedness was identified through workers' compensation as the expected payer or the presence of a work-related Ecode	2007-2011	N/A	Inpatient hospitalization (IH) and emergency department (ED) data from nine southeastern states USA	Relative Risk for different categories of independent variables	Survey, incidence	N/A	N/A
Harduar-Morano et al (44)	HRI was defined as the presence of an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM, morbidity or Tenth Revision (ICD-10, mortality) code for the effects of heat and light (992-992.9/T67-T67.9) or an excessive heat external cause of injury (Ecode) (E900.0/X30, E900.1/W92, E900.9) [	May and October (2005-2012)	N/A	Emergency department (ED) and hospital discharge data from the Florida Agency for Health Care Administration. Death certificate data from the Florida Department of Health (FDOH), Bureau of Vital Statistics	Crude rate ratios (RR) and corresponding 95% confidence intervals (CI)	Survey, incidence	N/A	N/A
Harduar-Morano et al (43)	HRI as occurring when: presence of (1) an ICD injury diagnosis code for the effects of heat and light (ICD-9-CM codes 992 or 992.0-992.9 or ICD-10 codes T67 or T67.0-T67.9) and/or (2) the presence of an ICD-9-CM or ICD-10 code for external cause of injury for excessive heat due to weather conditions (E900.0 or X30, respectively), excessive heat due to man-made conditions (E900.1 or W92, respectively), or excessive heat of unspecified origins (E900.9) or ICD-9-CM E900	2005 through 2012	N/A	ED visits and hospital Discharges. data on deaths for the same years from the Florida Department of Health, Office of Vital Statistics	N/A	Survey, descriptive	N/A	N/A
Mirabelli et al (70)	Heat-related deaths (ICD9 codes 692.71, 992.0-992.9, E900.0, E900.1, and E900.9)	1977-2001	Average annual summer temperatures	Medical examiner's records; statewide temperature data from the National Climatic Data Center	Rate ratio	Incidence	N.A.	N.A.
	According to the Maricopa County Department of Public Health surveillance system, using both the ICD-10 codes and key phrased in the text fields (a death was considered environmental heat-associated if it was related to heat generated by the climate (e.g., sun, humidity, etc.) and excludes heat from man-made sources such as ovens or manufacturing equipment.)	May-October 2002-2009	NOT specified	Death certificates	Assessing the risk of HR death by occupation	Case-control
	HRI International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) at least one among the following codes: 992.xx (Effects of heat and light), E900 (Excessive heat), E900.0 (Excessive heat due to weather conditions, or E900.9 (Excessive heat of unspecified origin)	From May through September 2008-2010	Daily maximum temperature	Emergency department (ED) data	Mean daily HRI ED visits for increase in daily maximum ambient temperature	Ecological	0	N.A.
Petitti et al (75)	Industry/Sector Codes Used to Identify Heat-Related Illness Claims OR ICD9 CM codes (705.1 Prickly heat 276 Hyperosmolality and/or hypernatremia Volume depletion Volume depletion, unspecified Dehydration Hypovolemia 584 Acute renal failure 584.9 Acute renal failure, unspecified 992 Effects of heat and light 992 Heat stroke and sunstroke Heat syncope Heat cramps Heat exhaustion Heat exhaustion, anhidrotic Heat exhaustion due to salt depletion Heat exhaustion, unspecified Heat fatigue, transient Heat edema Other specified heat effects Effects of heat and light)	January 1, 1995 to December 31, 2009	Maximum daily temperature (Tmax) and Heat Index (HImax)	workers' compensation claims	Mean Tmax and mean HImax for outdoor claims (TABLE III)	Ecological	0	N.A.
	The Type of Occurrence Classification System Other diseases and injuries; mental disorders; nervous systems and sense organ dis; skin and subcutaneous tissue dis; digestive system dis; resp. system diseases; infectious and parasitic dis; circulatory system dis; neoplasm; cancer	1 July 2001 to 30 June 2010	Daily maximum and minimum temperatures	Workers' compensation claim data	Incidence rate ratios (IRR) with 95% CIs, and interpreted as % in the N of daily work-related injury claims during heatwave periods compared with non-heat wave periods	Time-series	N.A.	≥3 consecutiv e days over 35°C);≥5 days of max temp in excess of 35°C OR ≥3 days of max temp in excess of 40°C
Rhea et al (82)	claims due to heat illnesses were identified using each of the following four codes: TOOCS nature classification G313 (heat stress/heat stroke), TOOCS mechanism classification G53 (exposure to environmental heat), TOOCS agency classification G7100 (weather and water) and TOOCS agency classification G7110 (sun)	2001-2010	Daily maximum temperature (Tmax)	Workers' compensation claim data	Incidence rate ratios (IRR) with 95% CIs,	Time series analysis/Case-crossover	N.A.	≥3 consecutiv e days with Tmax ≥35°C
Spector et al (89)	Definition of HRI	Study period	Heat index	Data source	Association measure	Type of study	Lag time	Definition of heatwave employed
	Reported sudden muscle cramps; nausea or vomiting; hot, dry skin; confusion; dizziness; or fainting	2012-2013	Reported "high temperature"	Data are from PACE4, a community-based participatory research project Participants were recruited from three agricultural counties. A total of 235 farm workers completed the baseline interviews	Prevalence of characteristics among different subgroups. Chi square test of differences	Cross sectional	N.A.	N/A
Xiang 2 et al (99)	Reported skin rash/skin bumps, painful muscle cramps/spasms, dizziness/light-headedness, fainting, headache, heavy sweating, extreme weakness/fatigue, nausea/vomiting, and confusion.	Interviews from Jul to Aug 2013	N/A	Eligible participants were: (1) 18 years or older; (2) farm workers engaging in outdoor crop production at the time of the interview; (3) able to speak English or Spanish; and (4) able to provide informed consent	Chi-square test and Fisher's exact test. Logistic regression models. Prevalence Rate.	Cross-sectional	N/A	N/A
	Heat-related symptoms were headache, tachycardia, muscle cramps in the arms or legs, fever, nausea, difficulty breathing, swelling of hands or feet, dizziness, vomiting and fainting. Dehydration symptoms were dry mouth and dysuria	February 2011	N/A	Harvesters were interviewed. A 64 items' symptom questionnaire with questions based on the US Military recommendations	Chi-square tests and Fisher's exact test	Cross-sectional survey with control group	N/A	N/A
Xiang et al (101)	Neurological symptoms Headache Loss of co-ordination Dizziness Tingling in hands/feet Blurred vision Fainting Electrolyte imbalances Abdominal cramps Spasms Systemic symptoms Fatigue Nausea Loss of appetite Early heat stress symptoms Heavy sweating Intense thirst Anxiety Dark coloured urine output Rashes Itching skin Dry mouth Elevated temperature Hot red or flushed dry skin	2013-2014 winter and summer	WBGT	Construction workers. Structured questionnaire	N/A	Cross sectional survey	N/A	N/A
	Symptoms of HRI (sudden muscle cramps; nausea or vomiting; hot, dry skin; confusion; dizziness; fainting; headache). The outcome of interest was experiencing three or more symptoms in the past week. Because HRI symptoms are common and general symptoms, using three or more symptoms was designed to improve the identification of HRI specifically	June 11-23, 2011	During data collection for the current study, temperatures ranged between 95°F and 104°F, and the heat index was 100°F or hotter every day, peaking at 108°F	Structured questionnaire	Ors Migrant farm-workers versus "ideal"	Cross sectional survey	N/A	N/A
Studies making use of ad hoc questionnair e surveys	Eight heat exhaustion symptoms (headache, nausea, vomiting, weakness, fatigue, dizziness, clammy/moist skin or irritability), and seven heat stroke symptoms (high body temperature, hot and dry skin, confusion, low muscle coordination, irrational behaviour, loss of consciousness or convulsions),	N/A	N/A	Data were collected from participants via a questionnaire. In completing the questionnaire, participants indicated whether they had experienced any symptoms of heat illness in the past 12 months.	Independent samples t-test One-way analysis of variance Pearson's Chi-square analysis Rate ratios were calculated for significant Chi-square observations	Cross-sectional with control	N/A	N/A
Paper	Symptom Feeling tired Cramps Nausea Dizziness Thirst Vomiting Confusion Muscle weakness Heat sensations Chills Feeling light-headed	N/A	WBGT	Direct measurements on workers and symptoms' referral	Independent samples t-test One-way analysis of variance Pearson's Chi-square analysis Rate ratios were calculated for significant Chi-square observations	Cross-sectional	N/A	N/A
Arcury et al (8)	Overall 42 symptoms, of them 18 MSK and the rest "General"	The survey was carried out in the middle of August 2001	WBGT	self-administered questionnaire	Chi2 test or Student's t-test	Cross-sectional	N/A	N/A
Bethel et al (11)	A section of Critical Incident Report was included in the worker data collection sheet to obtain workers' personal heat illness experiences. Reported symptoms of heat disorders include heat rash (1 case), fatigue (10 cases), feeling thirsty (3 cases), feeling discomfort (5 cases), dizziness (18 cases), difficulty in breathing (4 cases), heat cramp (3 cases), dehydration (3 cases), over sweating (4 cases), dry and hot skin (1 case), fever (8 cases), headache (6 cases), vomiting (8 cases), loss of control (2 cases), fainting (7 cases), non-sweating (1 case), and heat stroke (2 cases).	N/A	Predicted Heat Strain (PHS) model WBGT and many others	Data collection sheet for the construction workers sample, a questionnaire and interview guide for the managers sample and a site observation checklist	N/A	Ethnographic study. Qualitative study	N/A	N/A
Crowe et al (20)	A range of health symptoms including minor conditions such as heat cramps, heat syncope, and heat exhaustion to life-threatening heat stroke	August to September 2013	Mean maximum temperatures; Maximum heat index	interviewer-administered questionnaire that included standard questions related to heat-related symptoms	Logistic and log-binominal regression models were used to assess associations between sun protection behaviors and heat-related symptoms and to calculate prevalence ratios.	Cross-sectional	N.A.	N.A.
Dutta et al (24)	Only heat stroke considered	November 2003	None	Questionnaire	Multiple linear regression analysis (BODY TEMP registered)	Cross-sectional : no association between heat index and heatstroke was evaluated	N.A.	N.A.
Fleischer et al (31)	A variety of symptoms (e.g. increased thirst, excessive perspiration, itchy skin, tiredness, dry nose, blister formation, sinus problems, teary or burning eyes, exhaustion, malaise, dehydration, headaches, backache, leg pains, nose bleeds, premature baldness, dizziness)	March 2009	Hourly humidity and hourly maximum temperature	Focus group discussions and interviews	NONE	Cross-sectional	N.A.	N.A.
Hunt et al (46)	Subjective symptoms; Physiological parameters: Systolic and diastolic blood pressure and heart rate, electrolyte and blood urea	August 18th and 19th in 1998 ("fine days")	WBGT	Field study	Systolic and diastolic blood pressure and heart rate measurement before and during work Did not study association with WBGT data	Physiological parameters monitoring	0	N.A.
Pradhan et al (77)	Faint, tension, irritation, laziness, lack of sleep, rash, diarrhoea, eye infection, etc.	2010	Heat index, humidity index, and WBGT, based on the HOTHAPS approach	Household survey	None	Cross-sectional	N.A.	N.A.
Sahu et al (84)	NO MENTION OF HRI Health complains: pain in different parts of the body, digestive problems, CV problems, other problems (eye, ears, respiratory) ; Heat concerns (Aware of heat symptoms, discomfort or exhaustion during hottest days)	April to June 2011	WBGT	Questionnaire	Student t-test used to test for any significant differences between the measured parameters at different times and heat exposures	Cross-sectional	0	N.A.
Singh et al (87)	perceptions of heat discomfort, occurrence of health symptoms, heat exhaustion	summer of 2010	Not specified	semi-structured telephone interviews	No association measure used	Cross-sectional	N.A.	N.A.
Venugopal et al (92)	self-reported heat related health illnesses One of the following heat related symptoms at work i.e., excessive sweating, excessive thirst, tiredness, cramps, headache, nausea/vomiting, fainting or prickly heat	2 Seasons, once during the "hotter season" (April-June 2013 and another during the "cooler season" (November-January 2012)	WBGT (The minimum, maximum and standard deviation of WBGT values from each workplace was computed from the total number of ambient heat stress measurements taken at various locations in the each workplace).	Questionnaire	Chi square test was used to compare seasonal differences in qualitative assessments of heat for workers assessed in both hotter and cooler seasons.	Cross-sectional	N.A.	N.A.